Redefining hypoglycemia in clinical trials: validation of definitions recently adopted by the American Diabetes Association/European Association for the study of diabetes

OBJECTIVE The purpose of this study was to determine if the International Hypoglycemia Study Group (IHSG) level 2 low glucose definition could identify clinically relevant hypoglycemia in clinical trials and offer value as an end point for future trials.

RESEARCH DESIGN AND METHODS A post hoc analysis of the SWITCH (SWITCH 1: n = 501, type 1 diabetes; SWITCH 2: n = 721, type 2 diabetes) and the Trial Comparing Cardiovascular Safety of Insulin Degludec versus Insulin Glargine in Patients with Type 2 Diabetes at High Risk of Cardiovascular Events (DEVOTE; n = 7,637, type 2 diabetes) using the IHSG low glucose definitions. Patients in all trials were randomized to either insulin degludec or insulin glargine 100 units/mL. In the main analysis, the following definitions were compared: 1) American Diabetes Association (ADA) 2005 (plasma glucose [PG] confirmed ≤3.9 mmol/L with symptoms); and 2) IHSG level 2 (glucose confirmed <3.0 mmol/L).

RESULTS In SWITCH 2, the estimated rate ratios of hypoglycemic events indicated increasing differences between treatments with decreasing PG levels until 3.0 mmol/L, following which no additional treatment differences were observed. In SWITCH 2, the IHSG level 2 definition produced a rate ratio that was lower than the ADA 2005 definition. Similar results were observed for the SWITCH 1 trial.

CONCLUSIONS The IHSG level 2 definition was validated in a series of clinical trials, demonstrating its ability to discriminate between basal insulins. This definition is therefore recommended to be uniformly adopted by regulatory bodies and used in future clinical trials.