Exercise improves metformin 72-h glucose control by reducing the frequency of hyperglycemic peaks

Purpose To determine the separated and combined effects of metformin and exercise on insulin sensitivity and free-living glycemic control in overweight individuals with prediabetes/type 2 diabetes (T2DM). Methods We recruited 16 adults with BMI of 32.7 ± 4.3 kg m −2 and insulin resistance (HOMA-IR 3.2 ± 0.4) under chronic metformin treatment (1234 ± 465 g day −1 ) enrolled in a high-intensity interval training (HIIT) program. Participants underwent four 72-h experimental trials in a random-counterbalanced order: (1) maintaining their habitual metformin treatment (MET); (2) replacing metformin treatment by placebo (CON); (3) placebo plus two HIIT sessions (EX + CON), and (4) metformin plus two HIIT sessions (MET + EX). We used intermittently scanned continuous glucose monitoring (isCGM) during 72 h in every trial to obtain interstitial fluid glucose area under the curve (IFG AUC ) and the percentage of measurements over 180 mg dL −1 (% IFG PEAKS ). Insulin sensitivity was assessed on the last day of each trial with HOMA-IR index and calculated insulin sensitivity (C SI ) from intravenous glucose tolerance test. Results IFG AUC was lower in MET + EX and MET than in CON ( P = 0.011 and P = 0.025, respectively). In addition, IFG AUC was lower in MET + EX than in EX + CON ( P = 0.044). %IFG PEAKS were only lower in MET + EX in relation to CON ( P = 0.028). HOMA-IR and C SI were higher in CON in comparison with MET + EX ( P = 0.011 and P = 0.022, respectively) and MET ( P = 0.006 and P