Death Risk Rises With Blood Sugar
Even Without Diabetes, High Blood Sugar Ups Death, Heart Disease Risk
Sept. 20, 2004 -- As your blood sugar level goes up, so does your risk of death and heart disease - even if you don't have diabetes.
The news comes from two extraordinary studies appearing in the Sept. 21 issue of Annals of Internal Medicine. Both focus on a test called hemoglobin A1c -- HbA1c -- which measures average blood sugar levels over the past three months. Normal HbA1c levels range from 4% to 6%.
High HbA1c is known to be a marker for blindness, kidney disease, and nerve damage in people with diabetes. Now it also predicts heart disease in people with diabetes, report Johns Hopkins researcher Elizabeth Selvin, MPH, and colleagues.
That's a major finding, if not a major surprise. The shock comes in a British study that looked at HbA1c levels in people with and without diabetes. Regardless of whether a person had diabetes, the study shows that every 1% increase in HbA1c ups the risk of death -- from all causes -- by 24% for men and 28% for women. Nearly three-fourths of the deaths in the study came in people with "moderately elevated" HbA1c levels: between 5% and 6.9%.
"These are important studies because they show we should be concerned about blood glucose elevations even in people who do not have diabetes," Laurence S. Sperling, MD, director of the Emory Heart Center risk reduction program, tells WebMD.
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Selvin's team analyzed data from 10 studies of people with type 2 diabetes and three studies of people with type 1 diabetes.
In people with type 2 diabetes, they found, every 1% rise in HbA1c added 18% to a person's risk of heart disease. And there was a 28% jump in risk of "peripheral vascular disease" -- the problems in tiny blood vessels that lead to blindness, kidney failure, and amputation. The findings were similar, but not statistically significant, for people with type 1 diabetes.
"In normal people, HbA1c ranges from 4% to 6%. But in people with diabetes it can range from 6% to 20%," Selvin tells WebMD. "For people who have diabetes, good blood sugar control is an HbA1c of less than 7%. Over 8% is poor control. Over 9% is a very important sign of very poor control. Every 1% change is clinically significant."
People with diabetes already know they're supposed to keep their blood sugar under control. Now that advice is even more urgent. After all, Selvin notes, heart disease accounts for 70% to 80% of deaths in people with diabetes.
"The important question is whether HbA1c levels predict heart disease in diabetes. Our study says this is the case," Selvin says. "So if you keep good blood sugar control -- with good diet, proper exercise, and effective medication -- this can reduce your risk of heart disease."