Pre-Diabetes Doubles Risk of Heart Disease Death

In the Australian Diabetes, Obesity and Lifestyle Study (AusDiab), participants with impaired fasting glucose, a condition considered pre-diabetes, after five years were more than twice as likely to die of cardiovascular disease, said investigators at the International Diabetes Institute in Melbourne, Australia. Diabetes and pre-diabetes accounted for 65 percent of all heart disease deaths in the study of 10,429 Australians, they found.

Researchers classified participants as having known diabetes if they reported their physician diagnosing them with diabetes and were taking drugs to lower blood sugar or had blood tests that confirmed diabetes. Persons who had not previously been diagnosed with diabetes but had blood tests that indicated diabetes were classified as newly diagnosed diabetes.

After adjusting for other risk factors for heart disease mortality such as age, sex, history of heart disease, smoking, blood pressure, total cholesterol to high-density lipoprotein ratio, and waist circumference, the increased risk associated with impaired fasting glucose was about the same as the risk associated with known diabetes.

Compared with people who metabolized glucose normally, the five-year total mortality risk was 50 percent higher for people with impaired glucose tolerance and 60 percent higher for people with impaired fasting glucose. Study participants age 25 or older were enrolled in 1999 and 2000 and followed for a median of 5.2 years. At baseline, all participants underwent an oral glucose tolerance test, fasting serum total cholesterol, triglycerides and HDL measurements.

Impaired fasting glucose was defined as a glucose concentration of 6.1 mmol/l or higher, but less than 7.0 mmol/l, and two-hour plasma glucose of less than 7.8 mmol/l. Impaired glucose tolerance was defined as two-hour plasma glucose of at least 7.8 mmol/l, but less than 11.1 mmol/l and fasting plasma glucose of less than 7.0 mmol/l.

Researchers found that 298 deaths occurred during the median 5.2 years of follow-up, an all-cause mortality rate of 5.5 per 1,000 person-years with 88 of those deaths due to heart disease. Almost 12 percent of the people who had known diabetes when they entered the study died during follow-up, versus 6.2 percent of those newly diagnosed with diabetes, 5.2 percent of participants with impaired glucose tolerance and 3.9 percent of those who had impaired fasting glucose. The five-year death rate for those who had normal glucose metabolism at baseline was 1.7 percent.

Emergency Medicine News:Volume 29(11)November 2007p 35