OBJECTIVES: To investigate the association of severe hypoglycemia (SH) with all-cause mortality and complications among patients with type 2 diabetes mellitus (T2DM).

METHODS: Data were obtained from Tianjin Urban Employee Basic Medical Insurance database (2008-2015). Adult T2DM patients experienced SH events (ICD-10 codes E11.64, E13.64, E14.64, E16.x, and T38.3) were identified by primary diagnosis in inpatient or outpatient claims between January 1, 2008 and December 31, 2015, with the first date of SH event defined as index date. 1:5 propensity score matching was performed to form balanced pairs of SH and non-SH T2DM cohorts based on baseline demographic and clinical characteristics. Incidence of all-cause mortality as well as acute cardiovascular (myocardial infraction, angina, and arrhythmias) and cerebral vascular (stroke and transient ischemic attack) events were compared between SH and non-SH cohorts, and Cox regression models were conducted to investigate the association between SH and mortality and complication risks adjusting for baseline diagnostic history.

RESULTS: Among 279,030 eligible T2DM patients, 2,600 experienced at least one episode of SH. 1,452 SH patients were then matched to 7,260 non-SH patients in the retrospective cohort study (mean age 58.9 ± 11.1 years, 46.6% female) with median follow-up of 2.61 years. SH was associated with twofold risk of all-cause mortality (10.54% vs. 5.17%; HR=2.14, 95% CI 1.77-2.58, P<0.001). Patients in the SH cohort had higher incidence of transient ischemic attack compared with non-SH (10.54% vs. 8.03%; P<0.05), while the significance disappeared in the adjusted Cox analyses. No significant difference was observed for other complications.

CONCLUSIONS: In Chinese patients with T2DM, severe hypoglycemia is a potent marker of increased risk of all-cause mortality, but no significant association between severe hypoglycemia with acute cardiovascular and cerebral vascular events was observed. Further studies with longer follow-up period is needed in future.