The value of glycosylated hemoglobin (HbA1c) as a predictive risk factor in the diagnosis of diabetes mellitus (DM) in the elderly

Abstract

In order to evaluate the significance of HbA1c in the diagnosis of Diabetes Mellitus (DM) and the risk of future DM in the elderly, the HbA1c and the fasting glycemia of 2167 elderly subjects of 65-84 years were determined, taking part in the epidemiological Italian Longitudinal Study on Aging (ILSA). The subjects were divided in 3 groups according to their glycemic values, namely those with normal fasting glucose (NFG), with impaired fasting glucose (IFG), and diabetics. It has been revealed that the values of HbA1c in these 3 groups overlapped in more than 80%. The evaluation of the HbA1c levels represents a clearly lower diagnostic validity for the DM, than the fasting plasma glucose (FPG). The identification of new cases of DM in a follow-up of 3 years was modest: in the NFG group (2.35% among those who had an HbA1c<7.02 and of 2.99% of those who had HbA1c>7.02%), while in the IFG group the same analysis gave 14.14% of those with normal HbA1c, increasing progressively in parallel with the increase of the HbA1c values above 7.02%, reaching 19.59%. It is evident from these results, in agreement with the multifactorial characteristics of type 2 DM that one has to look for other predictive factors, such as the dysmetabolic lipid components, and first of all the genetic ones in the predictive diagnosis of DM.