September 2, 2008

Beta Blockers Worsen Blood Sugar--May Cause Diabetes

Many people know that it is a bad idea for anyone who takes insulin or a sulfonylurea drug to take a beta blocker. This is because it has long been known that these drugs block the counter-regulatory response that prevents a dangerous hypo or--if it cannot prevent the hypo--at least gives the victim some warning that one is coming by causing shakes and pounding pulse.

Now evidence from a huge study of almost 20,000 people has learned that beta blockers are dangerous to anyone with any blood sugar abnormality. The study is Anglo-Scandinavian Cardiac Outcomes Trial-Blood Pressure Lowering Arm (ASCOT-BPLA,). It was published in Diabetes Care in May.

Determinants of new-onset diabetes among 19,257 hypertensive patients randomized in the Anglo-Scandinavian Cardiac Outcomes Trial--Blood Pressure Lowering Arm and the relative influence of antihypertensive medication.

It concluded: "Baseline FPG >5 mmol/l, BMI, and use of an atenolol +/- diuretic regimen were among the major determinants of NOD [Non-insulin dependent diabetes i.e. Type 2] in hypertensive patients."

An analysis of the study (which is still only available as an abstract to non-subscribers) published in Irish Medical News explains "Hypertensive patients allocated to amlodipine and perindopril were found 34% less likely to develop NOD [Type 2] compared with those allocated to the β-blocker/diuretic combination."

Diabetes in Control adds the following: "Says Dr Anoop Misra, director and head (diabetes and metabolic diseases) Fortis Hospitals: "In patients with hypertension, beta blocker drugs are no longer frontline therapy. These drugs may not only increase blood sugar levels in those who don't have diabetes, but may worsen sugar control in those with diabetes and also blunt warning symptoms when low sugar occurs."

My mail suggests that American doctors are not aware of the negative impact of beta blockers on the blood sugar of their patients as many people with Type 2 who contact me are taking these drugs. My own doctors have also prescribed beta blockers for me in the past.

Here is a list of commonly prescribed beta blockers:

Generic name/Brand Name
cebutolol- Sectral
Atenolol (G)- Tenormin
Betaxolol- Kerlone
Bisoprolol fumarate- Zebeta
Carteolol hydrochloride- Cartrol
Metoprolol tartrate (G)- Lopressor
Metoprolol succinate- Toprol-XL
Nadolol (G)- Corgard
Penbutolol sulfate- Levatol
Pindolol (G)- Visken
Propranolol hydrochloride (G)- Inderal, Inderal LA
Timolol maleate (G)- Blocadren

CAUTION! Do NOT Stop These Drugs Without Help from Your Doctor

One of the nastier problems with Beta Blockers is that if you are taking one and stop it suddenly you raise the risk of having a heart attack. So if you are taking a beta blocker, you MUST contact your doctor and ask for guidance as to the safe way of getting off of it and onto a drug that is safer for people with diabetes.

There are alternatives to Beta Blockers. ACE inhibitors like Lisinopril do not raise blood sugar and also appear to have some kidney-protective qualities. Those who cannot tolerate ACE inhibitors usually do well on ARB drugs which include Diovan (Valsartan) and Avapro (Irbesartan). ARB drugs besides lowering blood pressure, also lower insulin resistance slightly. Though this effect is not usually detectable in people who are severely insulin resistant, I see an immediate impact on my own blood sugar when I take a dose of Diovan after not having used it in a while.

HCTZ (Hydrocholorothiazide, often abbreviated HCT) is a diuretic which is prescribed alone or combined in pills containing other blood pressure drugs. It has been shown to raise blood sugar. This may be because as a diuretic it eliminates water from the blood stream and this concentrates the glucose that is left. Whatever the explanation, if you can control your blood pressure with medications that do not contain HCT do so. Your blood sugar will thank you. Many doctors immediately prescribe the combination pills that contain this diuretic as a first line treatment, rather than prescribing the other drug alone. But if you cannot get adequate control with just the one pill, HCT may help. Just make sure you drink a lot of water with it.

Blood pressure control is as important as blood sugar control in preventing heart disease and stroke and it is thought that the overall improvement in stroke and heart attack statistics over the past decade are due to patients having better blood pressure control. So don't let this news make you avoid doing something about high blood pressure. Just make sure that the drugs you take to control your blood pressure are ones that are safe for people with pre- and full fledged diabetes.

Other ways to lower blood pressure are:

1. Cut way down on carbohydrates. Many people, though not all, will see dramatic drops in their blood pressure when they cut down on their carbohydrate intake.

2. Exercise.

3. Lose weight.

4. Eliminate salt from your diet. Whether this works depends on your genetic make up. For people whose genes make them salt sensitive, cutting salt causes a dramatic improvement in blood pressure. For others it has no effect.


Lili said...

I'm on a beta blocker, but it's not for hypertension. I remember my cardiologist saying it wouldn't cause more than a 20 point difference in my bg, but I dunno if he was talking out of his ass there. I do know that it doesn't really seem to affect my bg, but I have LADA, so who really knows. It's true that that I don't get certain low symptoms, but so far it hasn't been that big of a problem. Maybe the problem is more if you have insulin resistance? I don't know.

Arun.N.M. said...

Jenny, A word of caution. The fact that Beta blockers and especially Thaizide diuretics may worsen Diabetes is well known before this study. Also many studies have shown ACE inhibitors may prevent new onset of Type 2 Diabetes.

Only what this study showed is in white caucasian males who is having hypertension and 3 or more cardiovascular risk factors but no coronary artery disease or Diabetes,a regimen based on a calcium channel blocker to which an ACE inhibitor was added was associated with significantly less incidence of new onset type 2 Diabetes than a regimen based on Atenolol to which a thiazide diuretic was added.

Please note that Atenolol is one of the oldest of Beta blockers and is nowadays prescribed less and less.Newer Beta blockers have been designed to reduce the deleterious effects on blood sugar levels. Beta blockers have several cardiovascular benefits.
Also note that the entire study is funded by Pfizer the makers of Amlodipine with some help from Servier makers of Perindopril.

Anonymous said...

I have read that HCT brings out "hidden" diabetes. No one has ever been able to explain what "hidden" diabetes is. Can you explain ?

Jenny said...

"Hidden diabetes" is diabetes that your doctor missed because he or she only relies on the fasting glucose test to screen for diabetes.

It would have been easily diagnosed on a post-meal blood sugar test or a glucose tolerance test.

As you can see at and many people develop diabetically high post-meal blood sugars many years before the fasting blood sugar deteriorates. If doctors only test fasting blood sugars they'll miss it.

Arun.N.M. said...

Hidden Diabetes is not a Scientific term. Diabetes become revealed [even by post meal glucose or GTT] only when around 40 to 50 percent of your Beta cells in Pancreas have ceased to function.Some medicines can accelerate the time[months/years] taken for the Diabetes to get revealed. HCT or other Thiazide diuretics may cause hypokalemia and there by cause a reduction in pancreatic insulin output producing increased blood sugars.If your Pottasium level is maintained normally the chance of raised blood sugar with HCT is rare.HCT do not have any effect on Insulin sensitivity.

Unknown said...

I was prescribed a beta blocker for an irreglar heart beat two months ago and got tested A1C at 5.9 one month ago and came across this blog one week ago.

I'm a candidate to give a kidney to my wife, so now I'm on a health mission from God, working out every day, eating properly and this is the last thing I needed to learn (or first thing).

If the beta bloker bumps up my numbers up I could get disqualified as a donor, not to mantion damage myself. So I called the Doctor and expressed my concerns and his nurse called back and says not to worry. She had my blood work and I said "I'm on the border of diasaster. I'm at 5.9 of course I'm worried." She said you don't have to worry until 7.0 which mad me so angry I hung up.

Any ideas out there ??

Jenny said...


It is dangerous to stop a Beta Blocker suddenly, so DON'T! Talk to your cardiologist about your concern.

Unfortunately, they screen for donors with the Oral Glucose Tolerance Test which won't get better just because you are eating properly. There is someone in our extended family who needs a transplant and many otherwise healthy people were excluded because of the GTT results even though their blood sugar is fine in daily life.

So there is no easy answer as to what to do. I hope your cardiologist can give you some guidance, though he many not be aware of this side effect. The doctors I've consulted are often completely unaware of even very significant side effects of the drugs they prescribe.

You have my fervent wishes that you find a way to donate safely. The tests are given not only to protect you but to protect the person who receives the kidney too.

Kathleen said...

Thank you so much for this site Jenny -- I've gotten so much useful info!

Even before I discovered your info on beta-blockers, I decided my doc had messed up my A1C either by increasing BP med or thyroid med. I'd been stable for a year @ 5.8 (which I now realize thanks to you is not good enough!) but 2 months after she increased my meds my A1C was 6.3.

I do Postprandial Impulse Muscle Training to suppress spikes. This is extremely left ventricle strengthening, my resting heart rate is now in 60's. I decided I was too well controlled on BP's maybe having to compensate with another system to keep my BP up. I cut my atenelol in 1/2 to 25 mg.

I keep track of my heart rate as I do muscle impulses (1.5 minute, heart rate not > 130)

Question: Increased heart attack risk from high heart rate upon exertion -- it now seems much easier to get my heart rate up?

It is also now much easier to get my sugars down and keep them down!

I think I will ask her to get off the rest of it, substitute more Lisinopril.

I can't thank you enough!

By the way, I loved your commentary on early onset T2 and mitochondrial dysfunction. For all my muscle work, my VO2 max is poor, like in the papers. My Mom was diabetic, and of course I have her mitochondria.

If diabetes is due to mitochondrial dysfunction, I don't think there'll be a pill any time soon. We need to get those kids moving, frequently!

Jenny said...


Diabetes is due to many different causes--it isn't one condition, just a shared symptom. For some exercise is very helpful, for others it has no impact at all.

Unfortunately, most children with diabetes seem to be victims of genetic damage from chemical exposure in the womb and that isn't corrected with exercise.

I don't know about the relationship of heart rate on exertion to heart attack. I've always heard slow resting pulse was very healthy.

Finally, it isn't the A1c so much as the blood sugar spikes involved in getting there. If your 5.8% was achieved without going over 140 for any significant amount of time, it could be healthy. Some of us get higher A1cs that predicted, possibly because at normal blood sugars red blood cells live longer--and collect more glucose because of the longer life. Rely on meter readings, not A1c to determine health.

Natalie said...

I was put on a beta blocker (atenolol) for what I now know was Inappropriate Sinus Tachycardia. I would lay down in bed with a heart rate of 130, and if I did any exercise at all (NOT strenuous) it would go into the 150's and 160's. It was VERY uncomfortable, and I had edema and was short of breath. Of course, my BP went up too. This was before I developed diabetes, but I just don't see any alternatives. I was taken off the beta blockers recently when I had a diabetic coma, but as soon as I got out of bed, and started living a normal life again, my heart rate went right back up again. :-(

Anonymous said...

Natalie, your high heart rate could be due to too much salt, MSG intake. Look at the ingredients of everything you eat, snacks, condiments, everything.Not enough salt and you could die, too much and you could die. You could possibly get rid of those fast heart rate episodes like I did by cutting out too much sugar and too much salt and taking Magnesium suppliments. Magnesium also stops irregular heartbeat.

Unknown said...

Hello, I've been on beta blocker bisoprolol (Zebeta, Concor) for 10 years for too fast heart rate and not high blood pressure. All along this time, I started to see my blood sugar level go up (110-115 mg for fasting blood sugar in the morning). I could also notice a reduced capacity to effort (breathing) and a light erection problem. At rest, I also had a too slow heart rate (52 bpm) that made me feel tired. I asked my cardiologist to give me a beta blocker with less bradycardia effect and he gave me Nebivolol (Nebilet, Bystolic) and after 2 weeks already, my heart rate at rest is 62 (much better), my blood sugar dropped to normal (fasting 85-90 mg and 95 mg after meals), I feel much less tired, stand effort much more (breathe better) and have normal erections again because of vasodilatation effect of Nebivolol. So I assume everyone is different, but for me and my metabolism, Nebivolol is the king of beta blockers.

Jenny said...

Very interesting, thanks for the report!