High Hemoglobin A1c levels and glycemic variability increase risk of severe hypoglycemia in diabetic hemodialysis patients.

While hyperglycemia is central to the pathogenesis and management of diabetes mellitus, hypoglycemia and glucose variability also contribute to outcomes. We previously reported on the relationship of glycemic control to outcomes in a large population of diabetic end-stage renal disease (ESRD) patients. Recognizing that ESRD is a risk factor for severe hypoglycemia, we have now analyzed the association between glycosylated hemoglobin A1c (HgbA1c) levels and glycemic variability in those with hypoglycemia. This is a retrospective study of patients with diabetes enrolled in a large hemodialysis program. Hypoglycemia was identified from hospital discharge diagnostic codes. Glycemic variability was assessed by the standard deviation of HgbA1c and glucose levels over time. Hypoglycemia as a discharge diagnosis was documented in 4.1% of patients. Higher baseline HgbA1c was associated with greater risk for hypoglycemia hospitalization, a finding confirmed by time-lagged HgbA1c levels drawn a quarter earlier. Higher baseline HgbA1c categories were also associated with greater variability in HgbA1c levels during the analysis period. Similarly, greater glucose variability was associated with higher mean glucose levels by trend analysis. High, not low, HgbA1c levels are associated with greater risk of severe hypoglycemia, which may derive from glucose variability in the setting of treatment for hyperglycemia. High HgbA1c and glycemic variability are associated with increased risk of hypoglycemia in individuals with diabetes and ESRD.