Effects of exercising before breakfast on the health of T2DM patients—A randomized controlled trial

This is the first study to examine whether training before breakfast in the overnight-fasted state is more effective in improving the health of patients with type 2 diabetes mellitus (T2DM) than after breakfast in the fed state. Thirty T2DM patients (60 ± 8 years, 33.7 ± 4.6 kg/m² ) were randomly assigned to the F group (training in the overnight-fasted state (n = 15)) and to the C group (training in the fed state (control group, n = 15)). All patients completed an 8-week combined endurance/strength training program. Physical training significantly increased time to physical exhaustion during an endurance test (+10.4%), power output during strength tests (chest presses: +36.7% and seated rows: +37.8%), and fat-free mass (+1.7 kg). Body fat mass (-1.9 kg), glycated hemoglobin (HbA1c) values (absolute change: -0.3%), serum insulin values (-2.5 microU/mL), the homeostatic model assessment for insulin resistance (HOMA-IR) index (-1.1), and circulating triglyceride levels (-31 mg/dL) decreased significantly from pre- to post-training. The training had no effect on body mass index, serum fasting glucose, total cholesterol, low-density lipoprotein/high-density lipoprotein ratio or interleukin (IL)-6, IL-10 and tumor necrosis factor (TNF)α levels. Analyses of variance revealed no time × group interaction for any variable (P > .05). The training was effective in improving the health of T2DM patients. However, the preliminary study's data do not provide any evidence that the nutritional state (overnight-fasted or fed) in regular physical training plays a significant role for training-induced adaptations in T2DM patients. Full trials (using other training protocols as well) should be conducted to gain further knowledge about the relevance of pre-exercise breakfast ingestion.