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 HbA 1C 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. HbA 1C variability was determined by standard deviation of ≥3 HbA 1C results. Conditional logistic models were applied to determine association of HbA 1C variability with first and recurrent HH. Results In T1D, every 1.0% increase in HbA 1C 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 HbA 1C 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 P =0.07). The HbA 1C variability-HH association was stronger in more recent years in T2D ( P ≤0.004). Conclusions HbA 1C variability is a strong predictor for HH in T1D and T2D.