Common Misconceptions About Type 2 Diabetes
The Times on Type 2 Diabetes
Part 2 of 2
Blood Sugar and Heart Disease
Gina Kolata's recent story on diabetes in the New York Times is attempting to correct some common misconceptions about diabetes. In my previous post on this blog, I commented on her point that it's wrong to blame patients for their disease because it has a strong genetic component, and focusing on weight loss alone is not the answer.
Another point that Kolata emphasizes is that it's not just blood sugar control that is important in diabetes. Most people with diabetes die from heart disease, so patients need to control their cardiovascular risk factors as well. These include blood pressure and cholesterol levels.
I agree. But this idea is not new. The American Diabetes Association has had a campaign since the turn of the century for people to learn their "Diabetes ABCs," or A1c levels, blood pressure, and cholesterol levels. But again, apparently no one was listening.
How could a well-educated person like the mininster profiled by the Times not have known that people with diabetes are at risk for heart attacks? Why didn't his doctor tell him?
By focusing on this problem with the example of a type 2 patient attempting to control blood sugar levels (although they appeared a lot higher than I'd be content with) and still having a heart attack at a relatively young age, the Times is doing a good service. Perhaps more people will listen -- well, at least for a day or so until they move on to the next hot topic, like some new TV program or fashion trend.
But the Times also said that there is no evidence that reducing blood sugar levels will have an effect on heart disease risks. Yet there are several large, well-controlled studies out there that show that it does. One of the largest was the EPIC-Norfolk study, which showed that even in people without diabetes, the lower the A1c level, the lower the heart attack risk.
Those with A1cs under 5 had the lowest heart attack risk, and an increase of 1 percentage point resulted in a 22% increase in cardiovascular risk. And according to an editorial in the Annals of Internal Medicine, "When both diabetes and the actual hemoglobin A1c level were included in statistical models, only the hemoglobin A1c level (and not diabetes) remained a significant predictor of incident cardiovascular events or death, implying that a hemoglobin A1c level of 6.59% in a nondiabetic individual predicts a higher cardiovascular risk than a hemoglobin A1c level of 5.5% in a well-controlled diabetic individual."
[I'd think that anyone with an A1c of almost 6.6 would be diabetic, but sometimes the A1c doesn't track actual BG levels as well as it should.]
In other words, blood glucose levels are very important in lowering cardiovascular risk!
As the editorial states, "Thus, the presence or absence of diabetes is likely to become less important than the level of glycosylated hemoglobin in the assessment of cardiovascular risk (similar to the fact that a diagnosis of hyperlipidemia has become less important than the level of low-density lipoprotein cholesterol)."
Studies to determine whether reducing the A1c will also reduce the cardiovascular risk are planned. One would assume that it would, but until it's been proven, one can't say for sure. Sometimes high or low levels of something are associated with a disease, but changing those levels with drugs or supplements has no effect on the disease.
Nevertheless, I'd say there's a good chance that it will be proven that lowering your A1c will reduce your cardiovascular risk as well as reducing your risk of microvascular complications (kidney damage, eye damage, and nerve damage); for the latter there's already good evidence.
This doesn't mean you should ignore your blood pressure and cholesterol levels. These also important cardiovascular risk factors. But don't listen to the Times when it says there's no evidence that blood glucose levels are not important in preventing heart attacks. There is.