Diurnal Exercise Timing And Management Of Type 2 Diabetes Mellitus: A Randomised Controlled Trial

Regular exercise training improves glycemic control, which is a key objective in the clinical management of individuals with type 2 diabetes (T2D). Whether the magnitude of this improvement in glycemic control is altered by performing the exercise training in the morning or evening remains to be established. PURPOSE: To determine the effect of diurnal exercise timing on glycemic control in individuals with T2D. A secondary aim of the study was to assess changes in the soluble receptor for advanced glycation end products (sRAGE) and methylglyoxal concentrations to provide insight to potential changes in glucose metabolism. METHODS: Twenty sedentary adults with T2D (age: 59.7 ± 8.2 years; BMI: 30.8 ± 5.6 kg/m2; women: n = 6) were randomly allocated to either a morning (amEX) or evening (pmEX) exercise training group. The supervised 12-week (3 days/week) training program comprised of four resistance-based exercises (3 sets, 8-12 repetitions each) and 30 mins of moderate intensity walking. Outcome measures included changes in glycemic regulation (glycated haemoglobin, HbA1c; fasting blood glucose, FBG; insulin sensitivity, HOMA2-IR; C-peptide) and sRAGE, as well as postprandial glucose (PPG) and methylglyoxal concentrations measured during a mixed-meal tolerance test (MMTT) at baseline (pre) and post-intervention. RESULTS: Exercise training improved HbA1c and PPG excursions (main effect of time: both p < 0.01), but not FBG or HOMA2-IR (main effect of time: both p > 0.304). No significant group (amEX and pmEX) by time (pre- and post-intervention) interactions were observed for any fasting measures, or any measures during the 2-h MMTT (all p ≥ 0.38; Figure 3 & Figure 4) except C-peptide concentrations (p = 0.044), which had the greatest decrease in the pmEX group. There were no differences in methylglyoxal or sRAGE concentrations (All main effects ≥0.199). CONCLUSION: 12-weeks of multimodal exercise training improves glycemic control and postprandial glycemic responses in individuals with T2D, but these improvements occur independent of diurnal exercise timing. Supported by: This work was supported by the Diabetes Australia Research Program (General Grant)