Afternoon fed resistance exercise improves post-exercise glucose control in Type 1 Diabetes, particularly for MDI users.

Type 1 Diabetes (T1D) management is a complex balancing act, requiring meticulous insulin dosing to prevent both hyperglycemia and hypoglycemia. While regular exercise is crucial for overall health and insulin sensitivity, it presents unique challenges for individuals with T1D due to its acute effects on blood glucose levels. The timing of exercise and an individual's feeding status can profoundly influence these glycemic responses, often leading to unpredictable fluctuations. Current guidelines provide general recommendations, but specific, evidence-based strategies for optimizing resistance exercise timing to achieve stable glucose control, particularly in relation to meal timing, remain a critical gap for patients and clinicians.

This randomized crossover trial (TREX Study) involved 66 individuals with Type 1 Diabetes to compare the acute and nocturnal glycemic responses to different resistance exercise timings and feeding states. Participants completed three distinct acute bouts of resistance exercise: (1) morning (8 AM-10:30 AM) in a fed state, (2) morning (8 AM-10:30 AM) in a fasted state, and (3) afternoon (3-8 PM) in a fed state. Interstitial glucose levels were continuously monitored using CGM devices for 6-hours post-exercise and throughout the nocturnal period (11 PM-6 AM). The study design allowed each participant to serve as their own control, minimizing inter-individual variability.

Across all 66 participants, mean glucose levels were significantly lower in the 6-hour period following afternoon fed resistance exercise compared to morning fasted resistance exercise (8.65 ± 2.04 mmol/L vs. 9.46 ± 2.56 mmol/L, P = 0.04). No other significant differences were observed when considering the entire cohort. However, a more pronounced effect was noted in the subgroup of 47 participants using multiple daily insulin injections (MDI), but not in the 19 insulin pump users. For MDI users, in the 6-hour post-exercise period:

Mean glucose levels were significantly lower after afternoon fed exercise (8.44 ± 1.93 mmol/L) compared to morning fasted exercise (9.63 ± 2.58 mmol/L, P = 0.007). Time-in-range (3.9-10.0 mmol/L) was substantially higher in the afternoon fed condition (67.0 ± 27.6%) versus morning fasted (50.9 ± 29.5%, P = 0.007). Concurrently, time above range (> 10.0 mmol/L) was significantly lower in the afternoon fed state (26.3 ± 25.3%) compared to morning fasted (44.4 ± 32.1%, P = 0.003). These findings highlight the independent influence of exercise timing and feeding status on post-exercise glycemic responses.