Post-exercise glycemic control in type 1 diabetes is associated with residual ꞵ-cell function

OBJECTIVE To investigate the impact of residual β-cell function on continuous glucose monitoring (CGM) outcomes following acute exercise in people with type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS Thirty participants with T1D for ≥3 years were recruited. Firstly, participants wore a blinded CGM for 7 days of free-living data capture. Secondly, a 3-h mixed-meal test assessed stimulated C-peptide and glucagon. Peak C-peptide was used to allocate participants into undetectable (Cpepund 200 pmol/L) C-peptide groups. Finally, participants completed 45 min of incline treadmill walking at 60% VO2peak followed by a further 48-h CGM capture. RESULTS CGM parameters were comparable across groups during the free-living observation week. In the 12- and 24-h postexercise periods (12 h and 24 h), the Cpephigh group had a significantly greater amount of time spent with glucose 3.9–10 mmol/L (12 h, 73.5 ± 27.6%; 24 h, 76.3 ± 19.2%) compared with Cpeplow (12 h, 43.6 ± 26.1%, P = 0.027; 24 h, 52.3 ± 25.0%, P = 0.067) or Cpepund (12 h, 40.6 ± 17.0%, P = 0.010; 24 h, 51.3 ± 22.3%, P = 0.041). Time spent in a state of hyperglycemia (12 h and 24 h glucose >10 and >13.9 mmol/L, P CONCLUSIONS Residual β-cell function may partially explain the interindividual variation in the acute glycemic benefits of exercise in individuals with T1D. Quantifying C-peptide could aid in providing personalized and targeted support for exercising patients.