HbA 1C variability and hypoglycemia hospitalization in adults with type 1 and type 2 diabetes: A nested case-control study

Aims To determine association between HbA1C variability and hypoglycemia requiring hospitalization (HH) in adults with type 1 diabetes (T1D) and type 2 diabetes (T2D). Methods Using nested case-control design in electronic health record data in England, one case with first or recurrent HH was matched to one control who had not experienced HH in incident T1D and T2D adults. HbA1C variability was determined by standard deviation of ≥ 3 HbA1C results. Conditional logistic models were applied to determine association of HbA1C variability with first and recurrent HH. Results In T1D, every 1.0% increase in HbA1C variability was associated with 90% higher first HH risk (95% CI, 1.25–2.89) and 392% higher recurrent HH risk (95% CI, 1.17–20.61). In T2D, a 1.0% increase in HbA1C variability was associated with 556% higher first HH risk (95% CI, 3.88–11.08) and 573% higher recurrent HH risk (95% CI,1.59–28.51). In T2D for first HH, the association was the strongest in non-insulin non-sulfonylurea users (P < 0.0001); for recurrent HH, the association was stronger in insulin users than sulfonylurea users (P = 0.07). The HbA1C variability-HH association was stronger in more recent years in T2D (P ≤ 0.004). Conclusions HbA1C variability is a strong predictor for HH in T1D and T2D