Glycated hemoglobin and its spinoffs: Cardiovascular disease markers or risk factors?

Atherosclerosis is a major complication of diabetes, increasing the risk of cardiovascular related morbidities and mortalities. The hallmark of diabetes is hyperglycemia which duration is best predicted by elevated glycated haemoglobin A_1C (HbA_1C) levels. Diabetic complications are usually attributed to oxidative stress associated with glycation of major structural and functional proteins. This non-enzymatic glycation of long lived proteins such as collagen, albumin, fibrinogen, liver enzymes and globulins result in the formation of early and advanced glycation end products (AGEs) associated with the production of myriads of free radicles and oxidants that have detrimental effects leading to diabetic complications. AGEs have been extensively discussed in the literature as etiological factors in the advancement of atherogenic events. Mechanisms described include the effects of glycation on protein structure and function that lead to defective receptor binding, impairment of immune system and enzyme function and alteration of basement membrane structural integrity. Hemoglobin (Hb) is a major circulating protein susceptible to glycation. Glycated Hb, namely HbA_1C is used as a useful tool in the diagnosis of diabetes progression. Many studies have shown strong positive associations between elevated HbA_1C levels and existing cardiovascular disease and major risk factors. Also, several studies presented HbA_1C as an independent predictor of cardiovascular risk. In spite of extensive reports on positive associations, limited evidence is available considering the role of glycated Hb in the etiology of atherosclerosis. This editorial highlights potential mechanisms by which glycated hemoglobin may contribute, as a causative factor, to the progression of atherosclerosis in diabetics.