Seasonal Variation in Severe Glucose-lowering Drug-induced Hypoglycemia in Patients with Type 2 Diabetes

OBJECTIVE: Glucose-lowering drug-induced hypoglycemia is a serious complication and there have been a few reports of seasonal variations in hypoglycemia in patients with type 2 diabetes. The aim of the present study was to examine the association between severe drug-induced hypoglycemia and seasonal variations, and to elucidate the contributing factors. METHODS: This retrospective, single center clinical study, analyzed the cases of 125 patients who required emergency hospitalization for severe drug-induced hypoglycemia between January 1, 2001 and December 31, 2014. The period from November to April was defined as the cold season. RESULTS: Severe hypoglycemia occurred more often in the cold season than in the warm season. In the cold season, 62 of 9,981 (0.6%) emergency department visits involved patients who required hospitalization for drug-induced hypoglycemia. In contrast, in the warm season, 27 of 8,649 (0.3%) visits involved patients who required hospitalization for drug-induced hypoglycemia (p=0.002). The proportion of patients treated with sulfonylurea (SU) in the cold season was higher than that in the warm season. Even the use of low-dose SU caused hypoglycemia in the cold season. In the SU-treated group, the proportion of patients with white blood cell and/or C-reactive protein elevation was higher in the cold season than in the warm season (p=0.04). CONCLUSION: Severe glucose-lowering drug-induced hypoglycemia occured more frequently in the cold season than in the warm season, and was associated with an inflammatory state in patients treated with SU.