A1C: Predicting Diabetes in High-Risk Individuals

There are many known risk factors for diabetes: age, family history, weight, high cholesterol, and even race. In fact, many people are living with what is called "pre-diabetes", in which there are many risk factors present and blood glucose is higher than usual (but not high enough to be considered diabetes). It's important to be able to screen which of these individuals are at high risk for diabetes. Currently, some of the most recommended screening tests include the fasting blood glucose test and the oral glucose tolerance test; though accurate, these can be expensive and inconvenient.

A recent study by Lerner et al. shows that HbA1C, a value which indicates average blood sugar levels over months, can help to determine risk of developing diabetes. In over 10,000 patients, it was shown that an HbA1C value over 5.5% led to increased risk of developing diabetes over the next 5-8 years, with risk doubling for every A1C increase of 0.5%.

Currently, an A1C greater than 6.5% is considered diabetic, but the World Health Organization says that there is not enough evidence to interpret values below 6.5%. This study, on the other hand, supports the notion that perhaps A1C can serve as an efficient and easy screening tool, and that people with slightly elevated A1C (above 5.5%) may be at higher risk for diabetes. However, it must be noted that the majority of the 10,000 participants was already overweight, so using A1C as a screening tool may be most applicable to individuals who already have diabetes risk factors.



Sources:

1.

Lerner N, Shani M, Vinker S. Predicting type 2 diabetes mellitus using haemoglobin A1c: A community-based historic cohort study. European Journal of General Practice. 2013 Nov 29;1–7.

2.

American Diabetes Association. Screening for Diabetes. Dia Care. 2002 Jan 1;25:s21–s24.