For years high blood sugar has been a known risk factor for people with diabetes. A test called hemoglobin 1c (HbA1c) measures the average blood sugar levels over the past three months. A high HbA1c level increases a diabetic’s risk for blindness, kidney disease and nerve damage. It also increases the risk of heart disease, which accounts for 80% of deaths in people with diabetes.
A new study from the University of Cambridge School of Clinical Medicine has recently discovered that non-diabetics are also at much higher risk of heart disease and other fatal illnesses if their blood HbA1c levels are above normal.
The study, headed by Kay-Tee Khaw, M.D., appears in the September 21 issue of Annals of Internal Medicine.
4,662 men and 5,570 women between the ages of 45 and 79 years old participated in the study from 1995 to 1997, with a follow-up period to 2003.
It was discovered that for both men and women there is a strong relationship between high average blood sugar levels and cardiovascular disease. In fact, high HbA1c levels appear to be a risk factor for deaths from all causes. The study found that this is true even for people who do not have diabetes.
“Normal” HbA1c levels range from 4% to 6%. Three-fourths of the 521 deaths from all causes among study participants were people with moderately elevated average blood sugar levels between 5% and 6.9%. Those with the lowest rates of heart disease and death had HbA1c levels below 5%.
Every 1% increase in HbA1c increases the risk of death -from any cause – by 28% for women and 24% for men. These risks were independent of other risk factors, including age, body mass index (BMI), systolic blood pressure, cholesterol counts, smoking, or history of heart disease.
How significant are these findings for the average American? With every small increase in the average blood sugar level, even as small an increase as 0.1%, the risk of heart disease goes up. And only about 1/4 of our general population has average blood sugar levels in the safe 5% range. Unfortunately, the tendency is for our blood sugar levels to keep going up, as our obesity rate increases and our activity levels decline.
More studies need to be done, of course. But in the meantime, Dr. Khaw believes that we should all be attempting to control our blood sugar levels with more physical activity and diets rich in fruits and vegetables.