The rise and fall of HbA1c as a risk marker for diabetes complications

It is still unclear whether short-term, within-day, variability in glycaemic control is contributory to the development of diabetes micro- or macrovascular complications. However, consistent and compelling data are emerging that longer term fluctuations in glucose, as evidenced by increases in HbA1c variability, do indeed add to the mean HbA1c value in predicting the risk of microvascular disease. Until now, studies have found this to be the case mainly in type 1 diabetes, but in this issue of Diabetologia (DOI: 10.1007/s00125-012-2572-7) an analysis of the Tsukuba Kawai Diabetes Registry in Japan has found that HbA1c variability also predicts the risk of nephropathy in type 2 diabetic patients. These observations raise the possibility that reducing rises and falls in HbA1c may help avoid hyperglycaemia-related vascular disease without running the same risk of hypoglycaemia that a strategy focusing purely on lower HbA1c might incur.