May 16, 2011

When To Test Blood Sugar After Meals

For some reason the past week brought me a bunch of emails all asking the same question: Are we supposed to test our blood sugar one hour after we start or end a meal?

As is true with everything involving diabetes the answer is not simple due to variations in individual blood sugar responses.

The reason we test one hour after a meals is to learn how high our blood sugar goes in response to the specific meal. So we want to be testing at the moment when our blood sugar is at its peak.

Studies tell us something about the average time it takes for the carbohydrate in our food to turn into blood sugar (carbohydrates are the main nutrient that causes elevated blood sugars). Such studies suggest that most Americans who eat our meals fairly quickly will see a peak somewhere between one hour and seventy-five minutes after we start eating. But because studies only come up with averages, they don't take into account individual variations--and you are, of course, an individual.

And when we move from group averages to individual response we learn that when the blood sugar peak occurs depends on a multitude of factors that include how fast we eat our meals, how much we eat at each meal, how tightly bound the glucose is in the carbohydrates we eat, and how efficient our digestive system is at digesting the carbohydrate bound in our food.

That explains why the same meal consumed at the same time by two different people may peak at different times--and why I can't tell you exactly when to test.

That's why you might try varying the time at which you test a carefully chosen test meal to see if your personal peak is later than average. Choose a simple meal that contains a known quantity of carbohydrate--a single measured portion of something rather than a meal where you have to guess what you are actually eating. Test it on different days at a slightly different interval each time to see if your blood sugar might be peaking a bit later than average.


There are a couple things to keep in mind when you are testing your meals.

1. Hard Pasta (the kind that comes in dry form in boxes) takes several hours to digest and often will cause no rise in blood sugars at one or two hours. If you eat pasta you should test it at three and four hours to find a blood sugar peak. So-called "fresh pasta", however, digests at the same speed as bread. As discussed HERE Dreamfields Pasta produces the identical blood sugar curves as much cheaper normal pasta.

2. Pizza eaten with crust may also produce a delayed blood sugar peak due to the high fat content and the food volume involved.

3. Most people are more insulin resistant at breakfast than they are later in the day so you may see a higher reading after eating a food at breakfast than you will see if you eat the same food at lunch, even if you start the meal with the same blood sugar level.

4. If your blood sugar is very slow to come down after eating you may have elevated blood sugars left from a previous meal when you start eating your next. If you see much higher readings after dinner than you did eating the same food at lunch it is possible this is happening. In that case, you might want to test before you start eating, and if you see a high reading then, you would be well-advised to avoid eating any starch or sugar with your next meal. Eating only meat, green veggies, cheese and eggs won't raise your blood sugar significantly when it is already elevated.

5. If you have a condition called "gastroparesis" in which the stomach holds on to food for many hours at a time, delaying digestion, it may be impossible to predict when your blood sugar will be at its highest. This is not a common condition. It can be a diabetic complication, but usually it is a very late complication that affects people with Type 1 diabetes who have had very high blood sugars for decades. However gastroparesis can also be caused by other things that have no relationship to diabetes, for example, a viral infection.

6. Januvia, Onglyza, and Byetta all cause delayed stomach emptying (usually accompanied by constipation or cramping). If you are on these drugs, you may be experiencing blood sugar peaks later than usual and should experiment with later testing times.

7. Pure glucose--the sugar used in glucose tolerance tests--is absorbed directly from the stomach without having to be digested by enzymes. Other sugars have to be digested which takes longer. There is a theory beloved by nutritionists that says that whole grains and "complex sugars and starches" digest much more slowly than other carbohydrates, too. My experiences and that of many people with diabetes is that there is a difference in the speed with which glucose (and things like maple syrup or honey which contain pure glucose) hit the blood stream but that starch is pretty much starch (except for pasta) and whole grains digest at the same speed as potatoes or white bread. A study you can read about here confirms this.

Once you establish the interval after eating at which your blood sugar is likely to be at its highest, you need only test at that time to assess the impact of a new food (or meal) on your blood sugar.


But don't make yourself crazy worrying about the timing of the test. Because of the shameful inaccuracy of our overpriced blood sugar strips the readings these strips produce can easily be off by 10-15 mg/dl (approx .5 mmol/L) when blood sugar is in the range around 100 mg/ld (5.5 mmol/L) and by a lot more if it is over 200 mg/dl (11 mmol/L).

So when you test, look for ranges rather than exact data points. Your goal when you start testing is to find foods that keep your blood sugar in the low 100s (6s) and to avoid those that push it up into the 200s (11s) at any time. Very small differences in your readings--120 mg/dl compared to 128--are not significant because they fall within the range of meter error.

What you don't want to see is readings that are consistently in the range of 160 mg/dl and higher (8.9 mmol/L) at one hour after eating or readings that don't drop below 140 mg/dl (7.7 mmol/L) at two hours after eating. And consistency is key here. Readings that are high day after day are what we have to avoid. But if you see one or two high readings occasionally, don't panic.

That's because diabetic complications come from prolonged exposure to high blood sugars: from many hours spent above 140 mg/dl every day for months and years. An occasional brief high won't make you go blind. It's the overall pattern that matters here.


Both one and two hour readings are informative. The one hour reading tells us how high a food pushes our blood sugar. If we know how much carbohydrate there is in the meals that keep our blood sugar in the safe zone (learn what that is HERE) we can predict what other foods are safe to eat simply by looking up how much carbohydrate they contain. (You can find software and apps online that makes it easy to do this.)

The two hour reading tells us how efficiently our body was at getting rid of that temporary high. If it is elevated (over 140 mg/dl (7.7 mmol/L) it gives you warning that your blood sugar peak may be lasting long enough to start damaging your organs. If that is the case, you will need to cut back more on your carbohydrate intake or talk to your doctor about the safe medications that can help you achieve healthier blood sugar levels.

But it usually is a waste of time to talk to your doctor about your post-meal values until your readings are consistently over 140 mg/dl at two hours after eating. And even then they may dismiss your concern. That 140 mg/dl is the level that the American Association of Clinical Endocrinologists has set as the target that all patients with diabetes should be encouraged to reach. But most family doctors have been trained (by the American Diabetes Association) to believe that any two hour reading under 180 mg/dl (10 mmol/L) is "good control." This is, of course, why all the patients these doctors treat eventually develop diabetic complications, but it can be very hard to get treatment from a doctor who has absorbed this toxic ADA teaching.


There is one last, related issue that people write to me about which needs to be disposed of and it is this: If you test at half an hour after eating you are likely to see a high even if your blood sugar is completely flat at one hour. A surprising number of people write to me in a panic because they saw blood sugars over 140 mg/dl (7.7 mmol/L) half an hour or even fifteen minutes after eating.

A high shortly after eating is normal--as long as the reading has come down from that peak by an hour after eating. That is because, the way normal blood sugar control works, it may take a sharp brief spike in blood sugar to stimulate first phase insulin release.

But what makes a blood sugar response normal is that, in a normal person, as soon as this spike occurs, a burst of insulin is secreted which takes care of it completely. Blood sugar response is only considered abnormal if, after that initial blood sugar surge caused by glucose from a meal hitting the blood stream, the blood sugar level doesn't start heading back down.

You can see a graph of what happens to normal peoples' blood sugars when they eat a high carb breakfast HERE.



Scott S said...

Excellent advice! I would also add that your point about rules on when to test is well-taken; there is no bad time to test, and patients will learn something each time. However, many face limits on testing supplies, so doing tests at a variety of times may help them, but choosing time carefully using this info. can help them to make the most of limited supplies.

Jenny said...


The question of how to make the most of limited test strips is so important--especially now that so many insurer and single-payer health systems are denying Type 2s access to strips.

I have written about this issue on my page, A Diabetes Diet is Different From a Weight Loss Diet.

Since that page is so huge, I've copied the relevant text here.

Dealing with Limited Blood Testing Supplies

In in ideal world, we'd all have all the testing supplies we needed to control our blood sugar, but in real life blood sugar test strips are very expensive and many insurers sharply limit the number of strips people with Type 2 diabetes can get each month.

Here are some strategies that can help you if your access to strips is limited.

If you only have 50 strips to get you through a month, plan out what you are going to test ahead of time. Pick one of your favorite meals, and test at 1 hour after eating the first time you eat it and 2 hours after eating the second. Do this with a couple different meals and see if there's a pattern as to when you see the highest reading--whether it is at one hour or two. Then choose another meal and test it at the time when you saw the highest reading in the earlier meal. If you ever get a surprisingly low reading, try testing an hour later or earlier, to make sure you aren't missing the peak.

Make the goal of your testing be learning how many grams of carbs you can tolerate in one meal. If you learn that 30 grams is your upper limit, use software and your scale to find portions of other foods that will also clock in at 30 grams or less. Test one or two of these, and if you see the result you expect, you don't have to test every time you eat these foods again.

Wal-Mart sells a cheap and effective blood sugar meter with strips that cost one half as much as other vendors. Some drug stores also sell store brand meters with cheaper strips. If you need more strips, consider the $50 you pay for another 100 strips an investment in your health. It's far better to spend that $50 now, than to spend it on expensive doctor bills caused by complications you don't need to develop!

b said...

This is all very sensible advice but my diabetes is so weird that on a FBG of 4.5-5.0, I can easily go above 7.8 on a no-carb meal (e.g. 2-egg omelette). I can even manage to spike above that some mornings, on a cup of black tea with no sugar and just a small splash of milk.

So I had to chuckle a bit at the part about 'cutting back on carbohydrate' to avoid spikes. I don't know where I can cut back. How do you subtract from zero?

Jenny said...


Offhand I can think of two things that could cause the blood sugar rise that you describe.

1. Inappropriate releases of the stress hormones that the body uses to raise blood sugar in response to hypos. This sometimes happens if you are using too much insulin and giving yourself hypos that the body responds to too quickly for you to catch and measure them. Drugs that cause insulin secretion like glipizide can cause this too.

2. Inappropriate dumping of glycogen by the liver due to severe insulin resistance at the liver. Metformin might help if this is the problem.

Of course, there might be other reasons, too.

Unknown said...

Jenny, Thanks for another great post.

Especially grateful for your including mmol/L unit besides mg/dl, as mmol/L is often the unit used outside US & the glucose readings in your post are easier to follow without having to divide by 18 to convert from mg/dl to mmol/L.

In the 4th paragraph [ eat our mails fairly quickly ], you mean 'eat our meals' ?

Pls keep up the good work.

Good health to you & all readers.

Jenny said...

M, Thanks! It was a typo and it's fixed.

Brenda Bell said...

What we tend to forget about digestion is that ALL food -- including proteins and fats -- is broken down into sugars (and in the case of proteins, amino acids); therefore, it is possible to peak or spike after a "zero carb" meal without glycogen release coming into play.

Jenny said...

Brenda, 58% of protein can convert into sugar, but only very slowly over about seven hours. Only 10% of fat can convert to glucose, again, very slowly. Because of how slowly this conversion process takes place it isn't likely to cause a spike. And in people with Type 2 who have some ability to secrete insulin (i.e. they don't end up with blood sugars in the 600s no matter what they eat) the small amount of insulin secretion that happens over time is enough to mop up protein and fat.

It is almost always only people with Type 1 who have to worry about covering fat and protein with insulin.

Unknown said...

How about using CGM ( continuous glucose monitoring ) ? CGM eg. Dexcom will ensure that we don't miss blood glucose peaks by estimating blood glucose levels every few minutes.

Pls excuse slight digression : 1) in view of the availability of CGM, though it is rather expensive, and 2) your excellent article on switching to the real deal -- insulin -- when other medications can no longer control blood glucose, why don't every diabetics use CGM + insulin pump ? Because as you noted, it isn't just fasting but also after meals high glucose levels which can seriously damage organs. With CGM, we need not worry about when is the best time to check blood glucose, and an insulin pump of fast-acting insulin can manage dangerous blood glucose peaks.

Thanks for your & everyone's feedback.

Jenny said...

CGMs are wonderful. But they are extremely expensive because besides the pump you have to pay for the sensors which must be replaced every few days. Insurers won't pay for them for Type 2s.

It would be nice if doctors would let people wear one for a week or two to learn about their blood sugar. But I haven't heard of one doing this except as part of a study run by the monitor company. And in the study, the CGMS didn't display the blood sugars to the wearer! They were collected internally and only the doctor had access to them, making it almost impossible for the patient to learn the relationship of sugars to what they just ate.

But the people I've met with Type 2 who have used a CGMS tell me that they confirmed the usefulness of their regular finger stick testing.

Unknown said...

My endo provides a 72 hour CGM to evaluate BG during the day. My wife wore one and the information was shared with her so that she could see where the rough spots were.

Unknown said...

My wife is a T1 (55 years!!) and I am a T2. Our Endos share the same office and gave her a CGM for 72 hours, sharing the results with her to reveal the rough spots of her self care. That CGM is used for many patients, not me yet, but I would love to have one.

Frank said...

Not directly addressed here, but the point in the article about gastroparesis got me to wondering about the bodies absorption points and more specifically how duration between meals affects our glucose levels. Is fasting a viable alternative for some folks who are not as sensitive?
In the context of long term patterns my Md. has advised against drastic meal elimination because of my weight.

Jenny said...

For many people with diabetes, fasting makes the blood sugar go up unacceptably. But for others it might be a useful strategy. As is the case with so much, your meter will tell you.

I tried one of those diets where you eat very little every other day but found all it did was make me ravenously hungry when I did eat. Other people find it knocks the weight off. We are all SO different.

Frank said...

Jenny, The broad fluctuations in cholesterol also concerned us.

Natalie said...

A long time ago, when I wanted to find out my peak, I tested every half hour for 3 hours, numerous times, and found that it's pretty reliably 90 minutes after my first bite. I wouldn't quite have caught that if I had only tested on the hour.

I realize this kind of intensive testing may be impossible for those whose strips are limited, but the information it gave me has been invaluable.

As far as pumps and CGMs, I don't ever expect Medicare to pay for them for Type 2's. It's a numbers and therefore money game. Even though late-stage Type 2's, and particularly those on insulin could really benefit from them. Getting adequate strips is bad enough. :-(

John said...

Here in France, there appears to be a move afoot to limit access under the Health Service rules to two boxes (of 100) strips per year to type 2s.

So far, although my doctor has made noises to the effect that I'm using too many (4 a day now), he hasn't pushed it - perhaps because I don't currently need medication (thanks to our ignoring the French dietary "advice"). If he ever does press the issue, my stock of French rude works may get a serious airing!


Dana said...

I am 28 weeks pregnant and had a 3 hour glucose tolerance test today secondary being over the limit for my first, 1 hour test. I find my results to be questionable...perhaps you can explain. Upon arrival, my fasting blood sugar level was 74. I then drank a 100 gram dextrose solution. 1 hour following the test my blood sugar level was 180, 2 hours later, 190 and 3 hours later, 93. Does it seem odd to you that my 2 hour level was higher than my 1 hour level? I did not see my MD following the test, but the lab tech did indicate these are not results she typically encounters.

Jenny said...


Those results aren't highly abnormal from what I know. It's possible that the blood sugar level kept rising after an hour and then slowly dropped back again.

Since the readings were higher than you'd want, and doctors are aggressive about blood sugar control in pregnancy, your doctor will work with you to lower the levels to ones that are safer.

This will keep your baby from becoming unnecessarily large and, more importantly, from developing an abnormal glucose tolerance that could last through life due to exposure to high blood sugars in the womb.

k said...

Dear Jenny,
I have been having trouble with my diagnosis. I had strange happenings with my blood sugar after my thyroid was removed 3 months ago now. Within one month my A1C went from 5.4 to 5.6, and mean sugar from 104 to 122. The doctor doesn't think it's pre-diabetes... I also have sugar dropping like crazy right after I eat15 to 30 min. It goes to low 60's and 50's and then spikes to 140-150 one hour later...i also experience dizziness, neck pain and headache every time I eat... Is this something normal..

Jenny said...


Thyroid hormones affect blood sugar, and while your readings are technically normal, as your doctor says, because they stay in the range doctors consider normal, the way they fluctuate will make you feel wretched.

It's unusual to drop low in response to eating the way you do. It is possible that you are getting a burst of stress hormones to raise your blood sugar when it drops that low.

It is possible you are first getting a big burst of insulin after you first eat which is more than you need and causing the hypo which causes the counterregulatory reaction.

If it is due to the removal of your thyroid upsetting your hormone balance, it should get better as time passes and you get your thyroid hormones straightened out.

You might try taking a few grams of pure glucose right after you eat to counteract that initial spike. Glucose hits the blood stream faster than food. Use the table HERE to find out how much to use. That might prevent that intial hypo. It's worth a try.

Jenny said...


Thyroid hormones affect blood sugar, and while your readings are technically normal, as your doctor says, because they stay in the range doctors consider normal, the way they fluctuate will make you feel wretched.

It's unusual to drop low in response to eating the way you do. It is possible that you are getting a burst of stress hormones to raise your blood sugar when it drops that low.

It is possible you are first getting a big burst of insulin after you first eat which is more than you need and causing the hypo which causes the counterregulatory reaction.

If it is due to the removal of your thyroid upsetting your hormone balance, it should get better as time passes and you get your thyroid hormones straightened out.

You might try taking a few grams of pure glucose right after you eat to counteract that initial spike. Glucose hits the blood stream faster than food. Use the table HERE to find out how much to use. That might prevent that intial hypo. It's worth a try.

Sand_Al said...

Hi Jenny,
I recently discovered that my blood sugar is in the prediabetic range, so I've begun daily testing to identify my blood sugar patterns. For the most part, my 1 hour post meal readings are consistently higher than my 2nd hour readings (usually just by a few points), but every once in a while I'll get a reading where my 2nd hour levels are higher instead. I made sure to check that my carb intake was low (protein and veggies only) so I don't know if this is just a natural blood sugar fluctuation, but it has me curious. Could this just be the "meter range" issue you've mentioned, or is it that for some reason my blood sugar is actually peaking later?

Jenny said...

Sand_Al, If the values are airly close, say within a range of 10-20 mg/dl it could be meter error.

Another explanation could be that the valve at the bottom of your stomach opens unpredictably, delaying digestion. Or that the food you eat digests slowly for some other reason.

People do vary which is why laws laid down for everyone, or things like the Glycemic Index, based on averages taken at 1 or 2 hours from normal people can be so misleading.

Sand_Al said...

Thanks for the response, Jenny. It's so helpful to get a wider perspective. Your mention of the digestive process brings me to a second question ... I've read your book (pg 13) on first phase insulin release and the digestive process. However, I'm curious to know what happens for people who have problems with digestion, slow digestion or who don't fully digest their food (either through genetics, illness or aging). Does that have an adverse impact on first or second insulin responses?

Jenny said...


The second phase insulin response doesn't kick in until the blood sugar rises to around 120 mg/dl, which would be when some digestion had occurred.

But you're probably right that it could cause problems. I have a friend who had normal blood sugars but was diagnosed with a galky lower stomach valve who would get intense attacks of hypoglycemia.

Jenny said...

Mika posted this comment which was accidentally deleted:

I greatly appreciate this comprehensive information. I am 30 weeks pregnant and testing four times a day due to a borderline gestational diabetes test (glucose challenge) result. I was asked to test 60 minutes after my first bite. Since I am naturally a slow eater, this often means that I have barely finished eating when I test, and if I have had dessert, then there has just been a big sugar influx. Wouldn't it make sense then to wait 90 minutes? Or will I be "tricking" the test? With two little kids to manage, a busy life and a discomfort with blood, I don't have the luxury of testing more often just to see....

Jenny said...


The point of the hour test is to try to catch your highest reading. So you can try moving the test time by 15 minute increments until you locate when your personal peak occurs. There's no fear of gaming the test. The highs are what damage your body so you want to know how high they get. The time after eating is not the issue, though most people see that spike in that timeframe.

Carlie said...

Hi Jenny, I am recently having the same issue as K above, my glucose levels drop immediately after eating, but 2 hours later, they shoot up 60-70 points. This is confusing me as I cannot find much info on the net. I have a lap band, never been dxed w/ diabetes but keep eyes on my BG, my last A1C was 5.6 my last HDL:LDL ratio was 2.6 and TG were around 130. I can tell when the BG has risen b/c I get headache, a "heady" feeling sort of lightheaded but more like my head is in a fish bowl, sort of sick to my stomach, and the most frustrating is this labored breathing, like I can't catch my breath even while sitting still. My thyroid levels have never quite been stable, going from high to low then back again and they just adjust my synthroid accordingly, but my Endo is on maternity leave. Why is this delayed post prandial hyperglycemia? Please's quite debilitating

Jenny said...

Carlie, With a lap band, your digestion has been artificially slowed, which would make it possible that your blood sugar peaks later than usual.

But the symptoms you describe don't sound like typical reactions to high blood sugar. Many people experience no symptoms at all when they run high blood sugars, and others may feel a general malaise, or get overwhelmed by sleepiness, but labored breathing or sick stomachs don't sound like high blood sugars.

It is low blood sugars that give people the shakes and stress hormone symptoms. If you are running high sugars at 2 hours, have you tested at 3 or 4 hours to check that you aren't dropping into the 50s as a reaction? If you are dropping steeply that might cause some symptoms.

But you should discuss the labored breathing with your doctor, because it is not a classic blood sugar related symptom and should be checked out.

Unknown said...

Please can you advise on when to test after a long meal (more than one hour between first and last mouthfuls). It would appear that testing two hours after the first mouthful would also be testing at one hour after the (almost) last mouthful and the results would be difficult to interpret. These long meals are potentially a problem because of the likelihood of over-eating and a subsequent spike.

Jenny said...


Keep in mind your goal with testing is to make sure your blood sugar stays under your chosen target at all times. For many of us, that target is 140 mg/dl (7.7 mmol/L) as over that level much research shows that all complications become more frequent.

The less time you spend over your target the better off you'll be.

Practically, the best approach is to use shorter meals to determine how many grams of carb your body can handle, on average, and make sure any meal you eat, no matter how long, doesn't contain more than that amount of carb.

Unknown said...

Q : the glucose is absorbed in small intestine and chyme start entering the small intestine from stomach ,why sugar level rise during first two hours after meal ?

Jenny said...

I am pretty sure that glucose is also absorbed in the stomach. Beyond that, some foods digest quite quickly.

കരിപ്പാറ സുനില്‍ said...

What is the normal blood sugar level after 4 hour ,5 hour,.6 hour,7 hour of meal . If a person fasting what will be his blood sugar level . As you mention I have noticed that 15 minutes of meal blood sugar rises very largely ; what is the reason for that

Jenny said...

In a normal person blood sugar should have returned to the fasting range by 4 hours after eating, which is between 70 and 100 mg/dl. Pasta will sometimes digest slowly enough that it will cause a slight rise at those later times.

The rise at 15 minutes is due to the early digestion of sugars and starches in the food releasing the glucose from those foods into the blood. If the food contains pure glucose (also called dextrose) it will go into the bloodstream almost as soon as it hits the stomach too. Then the food that takes longer to digest will continue to be broken down and release more glucose over the next hour.

If the digestion is slow, which sometimes happens to people who have had diabetes for many years, the food may digest much more slowly and then the glucose from the food may reach the blood a lot later. In some cases this will cause the rise in blood sugar to occur a lot later than the usual hour after eating. Other problems with the stomach valves unrelated to diabetes can cause delayed digestion too.

Unknown said...

Newly diagnosed with T2. Just browsing around gathering info and came across your site. Jenny, there are few people who talk sense and give to the world what they are actually supposed to do. You are one of them. May you be blessed and be a Nightingale. Now my question, is it ok to have the prescribed diabetes pills an hour before you head to the pub in the evening. I am a one beer pint drinker or may sometimes a few whiskies!

Jenny said...


It probably depends on what the pills are. That's the kind of question best asked to a registered pharmacist. They tend to have a much better grasp of how drugs work than do the doctors who prescribe them.

Anne said...

This is very informative. Thank you very much. I'm really worried about my blood sugar level. Just after about 45 mnts after breakfast (white bread) my sugar level showed 233mg. Is it too high? In February 2013 a fasting blood sugar test showed 104 mg.

Jenny said...


The post-meal blood sugars deteriorate long before fasting sugars do, which is why the fasting blood sugar test is a poor test with which to screen for diabetes. Since damage is done when your blood sugar stays over 140 mg/dl for a few hours, your blood sugar probably is too high, whether or not your doctor decides, based on the worst screening test, that you have diabetes.

What you can do, right now, to improve matters is to use the strategy you'll find here: How to Lower Your Blood Sugar.

Many people find that is all they need. If it isn't enough, you will need to ask your doctor for help the next time you have an appointment..

Anonymous said...

Hi, I am 30 weeks pregnant and have been on a controlled carb diet and monitoring glucose levels at home due to a just over the limit 2 hour glucose tolerance test result. My question is, i have noticed that my peak after eating a smaller meal is around 45 minutes to 1 hour, but after a bigger meal (mainly lunch, with 50 carbs prescribed) it may peak only 1.5 or 1.75 hours after. Could this be due to my stomache being squeezed by pregnancy, and slower digestion? I have noticed it is worse if I lay down after eating. Thank you!

Jenny said...

Large meals that contain a significant amount of fat may take longer to digest for anyone. I don't know enough about the effect of pregnancy on digestion speed to say anything more than that.

Lisa said...

Hi Jenny,

Your website is a breathe of fresh air just when I needed! Thank you.

I am a T2, however am insulin dependant. After trying many oral medications and long acting insulin, I am now on 500mg metformin 3x daily, 40u 2x long acting insulin daily and approx 90-120u of fast acting insulin throughout the day. It seems I am more like a T1 than a T2. Even with limiting to 15g of carbs at a meal, I spike into a 14-18mmol/L range.
My father was diagnosed in his late twenties and died at 36 from the same extreme sensitivity.
Two Questions: First, any advice on how to try to get better control? My doctor and specialist both just keep telling me to keep trying different things... but I don't know what anymore!
Second, I keep dropping really low at about 2am (just over this last week) ranging from 2.3-3.9mmol/L and if I treat it, I wake up at 6am to a 11-14 range. Last night, I didn't treat it and I still woke up high, at a 8.6--it's really frustrating to feel like I cannot control my glucose. I'm often in the 18-25mmol/L range after a meal with any more than 15-30g of carbs. Guess I am just looking for some insight or new ideas on how to get my health under control. Doesn't help that I also take blood pressure and cholesterol medication. I am only 37 and this needs to change. Your ideas/suggestions/feedback/thoughts are all super appreciated!

Jenny said...


Sorry for the delay in replying, but Google did not notify me about your comment so I missed it.

I can't give advice as to how to dose your insulin, as that would be unethical. However, I can suggest that you ask your doctor or diabetes educator to help you adjust your doses by lowering your basal and raising your meal time doses. Those night time lows suggest your basal is too high, while the meal time peaks suggest that the meal time doses are too low.

Your doses are very much in the Type 2 range, but since they are not controlling your meals properly, the chances are you are extremely insulin resistant. Another possibility would be to ask to try U500 insulin, which is a concentrated dose of Regular Human Insulin where there is 5 times as much insulin in a unit as with the usual stuff. This kind of insulin sometimes works better for people who are very insulin resistant.

Nicole and Jose said...

Thank you for the great info in this post, very helpful! I was recently diagnosed with gestational diabetes under the newer, stricter Australian guidelines. All of my fasting and 2 hour post meal test levels have been normal (4-7 range). I was told recently to test at 1 hour post instead and noticed that (while normal) these levels are often lower than my 2 hour post test results (e.g. 6.3 at 1 hour, 6.8 at 2 hours). Is this normal, a problem, or could it be that that's just when I spike? I don't often test at 3 or 4 hours post because I snack often due to being pregnant. The few times I have tested 3 hours post the levels had come down a tad to 6.3 (after a heavy meal). Is this ok? Any thoughts? Also am i right in not eating/snacking while waiting to test post meals? Thanks!

Jenny said...

Probably being pregnant has slowed your digestion. The glucose from digested food mostly gets into the blood when the stomach has released the food into the gut.

Re the snacks, your goal in testing is to make sure your blood sugar is not being pushed to high at any time. The carbs from snacks will add to the effect of carbs from meals and extend the time your blood sugar is high. So if you are snacking a lot, it is a good idea to test now and then to be sure that your meals plus snacks are still controlling your blood sugar.

However, if the doctor wants to know what specific meals are doing, you probably shouldn't confuse the matter by snacking later, as the carbs in the snack will raise your blood sugar again.

A simple way to deal with this would be to snack on foods that are protein and fat only, with no carbs, like meat, cheese, eggs, and greek yogurt (the carbs on the label have been fermented away),

Sarah said...

For example, last night, after a small, 90g baked potato as a part of my dinner, my bg rose to 174 at 30 min. By one hour it had fallen to 130, and at 1:30 it had fallen to 110. Is this still considered a normal pattern? How high can an initial 30min spike rise and still be considered normal? Thanks!

Jenny said...

Sarah, That would definitely be considered a normal pattern. There is no data on spikes before 1 hour mapping to any bad health outcome..

Sarah said...

Do you have any idea as to the mechanism behind this difference in effect?

Jenny said...

Glucose that remains in the blood for a while starts to bond to the blood vessels which over time damages them. When the sugar is immediately removed from the blood as it does with those brief spikes, this doesn't happen.

sarah said...

hi my BS was 174 30min after a meal then few minutes dropped down to 138 two hours later was 108 is that normal i dont have daibetes just check it suddenly by my mom meter !!!! my period will come after few days is it related to my first number ???thanks alot

Jenny said...

Most doctors would consider those to be normal readings, though they are at the higher end of normal. But in the week before a period many women do become more insulin resistant which would raise those numbers.

I wouldn't worry about them. If you have a family history and want to avoid diabetes, just cut back on how much starch and sugar you eat. Lowering carb intake will take some of the stress off your beta cells and preserve their function.

Unknown said...

The placenta, which is the equipment system for the fetus, is conceived to be the underlying cause of this situation. It produces a large quantity of testosterone during a maternity and some of this testosterone alters the effectiveness of the mother's blood insulin.

Unknown said...

before food 90 after food 139 is it ok ?

Jenny said...

GS, Those readings would fall into the normal category.

Jody said...

I seem to get 2 spikes. One around an hour that goes down quickly, and then at maybe an hour and a half or hour and 45 minutes if I had a big meal with some carbs or it's also happened with popcorn, I'll then have a pretty fast moving spike up all the way into the 170's, then it drops FAST - the whole spike will only last maybe 20-30 minutes and the only reason I even catch it is because I'm testing between that 1-2 hour mark that most tell you to test. Is this normal? What causes it? I am 43, low BMI (about 20), eat a good diet but not a saint (I enjoy popcorn occasionally or a meal out occasionally but otherwise try to eat moderate carb and real food). I exercise a lot, too. Strong family history of diabetes. Fasting glucose in high 90's or low 100's.

Unknown said...

Hi Jenny,
I am now 30 months pregnant and tested for blood sugar which showed high level reading so advised by doctor to take 4 units insulin (Mixtard30/70) initially. I am taking insulin twice per day before breakfast and before dinner and suggested to have food after 15min of insulin.
I took food in regular intervals
Fasting was 120
After 15min of insulin I took 2 chapathis at 9AM and after 2hr reading blood sugar was 160,
At 11.30AM I took 2 chapathis ,
At 2PM 1cup Rice and after 2hr reading blood sugar was 120,
5 PM 1 cup Rice ,
7.30 PM 2 wheat dosas and after 2hr reading blood sugar was 190
Now i am advised to take 8unit because of high reading 190.

I usually take white rice for lunch but i get only less than 130 for it.I tried 2 chappathis but got more reading than rice during breakfast and dinner. Please tell me why this reading is not showing less for wheat foods .Also i get different reading for same food in morning and dinner.Usually i notice more in reading taken after dinner.

Jenny said...


You are probably starting from a higher blood sugar at the end of the day because there is still glucose in your blood from previous meals.

You are probably getting more grams of carbohydrate (starch in this case) in the wheat foods than in the rice. The total number of grams of carbs you eat will determine how much glucose goes into your blood when the meal digests.

If you can replace the rice and wheat with foods richer in protein and fat eggs, cheese, and nuts, or perhaps lentils, you will be taking in fewer grams of carbohydrate and that should result in a lower blood sugar.

Wheat foods can be very dense and pack a lot of starch into a small area.