The effect of 6-day subcutaneous glucose-dependent insulinotropic polypeptide infusion on time in glycaemic range in patients with type 1 diabetes: a randomised, double-blind, placebo-controlled crossover trial

Aims/hypothesis Type 1 diabetes is characterised by reduced glucagon response to hypoglycaemia, increasing the risk of insulin treatment-associated hypoglycaemia known to hamper glycaemic control. We previously reported a glucagonotropic effect of exogenous glucose-dependent insulinotropic polypeptide (GIP) during insulin-induced hypoglycaemia in individuals with type 1 diabetes. Here we investigate the effect of a 6-day s.c. GIP infusion on time in glycaemic range as assessed by continuous glucose monitoring (CGM) in individuals with type 1 diabetes. Methods In a randomised, placebo-controlled, double-blind crossover study, time in glycaemic range (assessed by double-blinded CGM) was evaluated in 20 men with type 1 diabetes (18–75 years, stable insulin treatment ≥3 months, diabetes duration 2–15 years, fasting plasma C-peptide below 200 pmol/l, BMI 20–27 kg/m 2 , HbA 1c <69 mmol/mol [8.5%]) during two × 6 days of continuous s.c. GIP (6 pmol kg −1 min −1 ) and placebo (saline [154 mmol/l NaCl]) infusion, respectively, with an interposed 7-day washout period. The primary outcome was glycaemic time below range, time in range and time above range. Results There were no significant differences in time below range (<3.9 mmol/l, p = 0.53) or above range (>10 mmol/l, p = 0.32) during night-time or daytime, in mean glucose, or in hypoglycaemic events as assessed by CGM. GIP altered neither self-reported hypoglycaemia nor safety measures. Compared with placebo, GIP significantly increased time in tight range (3.9–7.8 mmol/l) during daytime (06:00–23:59 hours) by [mean ± SEM] 11.2 ± 5.1% [95% CI 0.41, 21.9] ( p = 0.02). Conclusions/interpretation Six-day s.c. GIP infusion in men with type 1 diabetes did not procure convincing effect on overall time in range, but increased time in tight glycaemic range during daytime by ~2 h per day. Trial registration ClinicalTrials.gov NCT03734718. Funding The study was funded by grants from The Leona M. and Harry B. Helmsley Charitable Trust and Aase og Ejnar Danielsens Fond. Graphical abstract