Fluctuations in glycosylated hemoglobin (HbA1C) as a predictor for the development of diabetic nephropathy in type 1 diabetic patients

ObjectiveThe incidence of diabetic nephropathy is higher in type 1 diabetic patients with associated risk factors. The within individual fluctuations in HbA1C and its effect on the development of nephropathy was not previously studied. The purpose of this study is to examine whether HbA1C fluctuations are a predictor of the development of diabetic nephropathy independent of mean HbA1C and other risk factors.MethodsOne hundred and seventeen patients (64 females and 53 males) were recruited and followed up regularly at least every 3 months. The “fluctuations” in HbA1C over time was assessed. HbA1C fluctuation was defined as an increase in HbA1C of more than 2% between two consecutive measurements, or an increase of more than 1% at 2 points in time.ResultsIncipient nephropathy was present in 18 and absent in 99 patients. Mean HbA1C was significantly higher in nephropathy than in non-nephropathy patients. The effect of fluctuations on nephropathy appeared to be more significant in patients with poor metabolic control (HbA1C ⩾ 8%).ConclusionT1D patients who have a similar mean HbA1C may progressively behave differently in terms of developing nephropathy, depending on the fluctuations in HbA1C. This effect seems to be more pronounced among those who have higher values of HbA1C.