June 5, 2008

How Long Does It Take to Develop Complications?

If you've been diagnosed with diabetes you may well be terrified that you will develop the horrible diabetic complications you have seen ruin the lives of relatives who also had diabetes. You've seen your loved ones' feet literally rot off, their kidneys fail, their eyes grow dim. Now, you fear, it will be your turn.

But it doesn't have to be!

To understand why the horrors of complications devastate people with diabetes and why they don't have to ruin your life you have to understand something about the natural history of these complications: how long they take to develop and what research has found about what can slow them down or stop them.

You won't develop any diabetic complication immediately after the onset of diabetes--though because so many people with Type 2 diabetes have had undiagnosed diabetes for 5 years or more, many people with Type 2 diabetes do already have complications on the day of their diagnosis.

The most common diabetic complication found in these "newly diagnosed" Type 2s is neuropathy--pain or numbness in the nerves, usually of the feet, followed by protein in the urine--a sign that the kidney filtration units are getting clogged, and early retinal changes.

But if you get an early diagnosis, it is almost certain you will have none of these complications at diagnosis, because studies of people with both Type 1 and Type 2 diabetes suggest that it takes about 5 years of exposure to high blood sugars for any of these complications to develop. For example, one study of Type 2s who had no retinopathy at diagnosis found that at 6 years after diagnosis 22% (1 in 5) had developed some retinopathy. The study states, "Development of retinopathy (incidence) was strongly associated with baseline glycaemia [high blood sugar], glycaemic exposure over 6 years, higher blood pressure and with not smoking."

A Japanese Study tracked the development of retinopathy and kidney dysfunction and found that at 6 years between 32 and 44% of those using an old-fashioned, inadequate twice a day insulin dosing schedule and only about 8% in those using the more modern basal/bolus insulin regimen had developed retinopathy (or seen it get worse). A very similar pattern was found in the progression of kidney dysfunction.

Surprisingly, there is very little research on the development of neuropathy. What little there is (discussed in detail here: Research Connecting Organ Damage with Blood Sugar Level suggests that neuropathic damage starts out when blood sugars are in the poorly named "pre-diabetic" range when small nerve fibers are affected and moves to larger fibers as blood sugars are allowed to rise over 200 mg/dl as they do in the people with Type 2 diabetes who attempt to control their blood sugar with nothing more than pills and hence have an average A1c according to the NHANES III data near 10%.

But it is the slowness with which diabetic complications develop, ironically, that has a lot to do with WHY they occur at all. Because it takes so long for them to develop, people with diabetes may go for years with blood sugars surging into the 200s--which they may not even know about, since their doctors tell them to test only their fasting blood sugars once a week, without experiencing any complications. Because they don't develop detectable complications during these early years they assume that they are somehow magically protected and that their mediocre blood sugar control is not harming them.

Then, one day, six or even ten years later, the doctor gives them the bad news. There are abnormal blood vessels in their retina. There's protein in their urine. That infection on their foot is not going to heal.

Sadly, many of these patients have been under a doctor's care and many have been achieving the 7% A1cs their doctors have told them is "excellent control" though of course it is far from that.

That's because almost all the major research studies that attempt to connect the progression of complications with blood sugar level accept 7% A1cs as the lowest possible blood sugar level you could attain. They show that the development of complications is slowed when you maintain a 7% A1c as opposed, say to a 10% A1c. But they also come up with something else: if you have Type 2 diabetes as opposed to Type 1, your chance of developing complications when you maintain that 7% A1c is still very, very high.

Type 1s have far fewer complications at the 7% A1c level, possibly because they achieve that A1c by seesawing swiftly between 60 and 400 while Type 2s are more likely to get the same 7% A1c by spending all their time between 180 and 250. It appears that it is the hours spent at high blood sugar levels that don't swiftly drop low that bind the glucose to your nerves, blood vessels and kidney filtration units.

There is no major research that looks at the progression of complications in people diagnosed with diabetes whose A1cs is in the 4.5-6% range and whose blood sugar is kept under 140 mg/dl. But we know from multiple studies by neurologists that people NOT diagnosed with diabetes whose blood sugar stays under 140 mg/dl on glucose tolerance tests almost never have neuropathy while those whose blood sugar is routinely going over that level, whether diagnosed or not do have more neuropathy. And we also know that people whose blood sugar stays under 140 mg/dl have a much lower incidence of heart attack than those with or without a diabetes diagnosis whose blood sugar after a glucose challenge is higher.

So what is the take home message from all this?

It's simple. Keeping your blood sugar in the normal range and controlling your blood pressure probably will prevent you from experiencing the horrors of diabetic complications. Your relative who lost his or her leg did so because their doctor allowed them to walk around with blood sugars well over 200 mg/dl after every meal for decades. Those bad kidneys likewise result from many years of exposure to very high blood sugars, along with some other factors including poorly controlled blood pressure and, possibly, overuse of painkillers like Tylenol and Advil and drinking too much Coke and Pepsi, even the diet kind.

But for those of you who are conscientious, it cuts the other way too: three days or even three months of high blood sugars aren't going to make you go blind. Three years, is a different story. But if you have been doing really well for a year or two and get off track for a few months, you aren't doomed. And if you have been the victim of poor medical advice and have been running those 7% A1cs and over 140 mg/dl blood sugars for years because you were told that was all you needed to do and are starting to see complications, there is still plenty of time to prevent them from getting worse and possibly--if you are willing to really work at it--to reverse them.

Normal blood sugars are possible, and over the almost ten years I've been observing the diabetes scene things have improved immensely. A 2008 poll on tudiabetes.org, a social media site for people with diabetes,  revealed that 20% of the members of that community--many of them people with Type 1 diabetes, had A1cs in the normal 5% range. If that poll had been run a decade ago, the number with that kind of A1c might have been only 2%!

So if you're terrified of complications, use that fear to motivate you to make sure you never have to experience them. Keep your A1c in the 5% range using whatever it takes. Cut the carbs, demand a modern insulin regimen. If you can afford it, get a continuous glucose monitor. All these techniques work. In another 30 years it is my belief we will have a generation of people who have lived with diabetes for decades, both Type 1 and Type 2, who will look at the incidence of horrifying diabetic complications common in the 1990s and even now as being as unnecessary as the hundreds of thousands of deaths from cholera that occurred throughout the 19th century when people did not understand the dangers of drinking from wells contaminated with human sewage.


Anonymous said...

Great post. I had neuropathy (misdiagnosed as gout for several years) yet my A1C was only 5.3%. Following the advice you give, I have reduced my A1C to 4.7% and greatly improved my neuropathy. It's not gone but it is much less noticable. I have done this with no medication--diet and exercise only. When I eat carbs, I match my exercise to my intake so that my blood sugars never go over 140.

water said...

Is the vagus nerve considered large or small nerve fiber?

Jenny said...

That's a good question!

My understanding is that the vagus nerve starts thick and then travels through the body getting smaller (like the branches of a tree) so it may well be a combination of both.

Ashley D. Miller said...

Dear Jenny,

I was searching on Google for articles on how long it takes to develop diabetes complications and I came across yours. I was diagnosed a few years ago.
I've known the risks and about A1c numbers and whatnot since I was diagnosed. I guess I have been in denial. I have been in the 300s and have had an A1c in the 10s, and yet, I still lacked motivation to get healthy.
I thought, "well I'm only 26 and not obese, so I'll be okay." I know deep down that's not true and that I'm killing myself. I'm always scared. I cried after reading your article. I realize now how real it is and I just hope I'm not too late. I hope more people read your article and get smart. Thank you.


Ashley Miller

Jenny said...


Sorry not to respond earlier, but the notification that you'd posted a comment seems to have not gone through.

If you are seeing blood sugars that high and are young and normal weight you probably have some defect in insulin production that means you need to find a skilled endocrinologist to put you on the kind of insulin regimen that may be the only effective treatment. The good news is that the right kind of insulin regimen can help you get normal numbers. I'd urge you to read Dr. Bernstein's Diabetes Solution and John Walsh's Using Insulin to get a feel for the kind of regimen that might work for you so that you can find a doctor who is up-to-date and can help you.

Mmmeee said...

oh my gosh im so scared ive had diabetes for 18 years and i would say probably 12 of those years on and off ive had good control now i just had eye laser in one eye i feel tingling in my hands and feet and legs and i get aching lower back to the side ive lost a lot of teeth and my sight is worse i have 4 young children iam 27years old and i wreaked my future nothing can explain how hopeless and down i feel

Jenny said...

Melanie, It is NOT too late to improve your health. Can you see an endocrinologist who can help you get much better control? Diabetes treatment for the kind of diabetes you have has changed since you were young. Better ways of dosing insulin and pumps help. Health insurance is more available. Fight for your right to get better treatment.