Aerobic exercise improves fat oxidation capacity and reduces insulin resistance levels in patients with type 2 diabetes mellitus: Preliminary results of the EDUGUTION study

Resumen

INTRODUCTION: The practice of physical exercise is essential in patients with type 2 diabetes mellitus (T2DM). However, itis currently unclear which type of exercise is the best therapeutic tool for T2DM management. Thus, the aim of this randomized controlled trial was to analyze the effect of an aerobic training program, moderate-intensity continuous training (MICT) vs. high-intensity interval training (HIIT), on glycemic control and the maximal fat oxidation capacity during exercise (MFO) in people with T2DM.METHODS: A total of 27 adults (n=11 females; 54.5±8.9 years; Body Mass Index=34.2±5.6 kg/m2) with T2DM were randomized into three groups: HIIT (n=7), MICT (n=9), and control group (CG) (n=11). The 12-week training consisted of three sessions per week, HIIT included 10×1 intervals pedaling at 90% of peak power output, and MICT consisted of continuous pedaling at 10% above the first ventilatory threshold for 50 minutes. Before and after the intervention, fasting blood samples were taken and glucose, insulin, and glycosylated hemoglobin (HbA1c) were analyzed. The homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. The MFO was determined by indirect calorimetry with a gas analyzer with 15W/3-min increments. Then, after a 5-min resting period, a maximal test with 1-minute steps (15W) was performed until exhaustion. To examine the effect of the intervention, a 3×2 mixed ANOVA with repeated measures was used.RESULTS: No statistically significant differences were found between groups at the beginning of the intervention (p>0.05).After the intervention, a main effect of time was observed for basal insulin levels (F(1,24)=5,73; p=0.025; ηp2=0.19) andHOMA-IR (F(1,24)=4,75; p=0.039; ηp2=0.17). Moreover, a significant time x group interaction was observed for MFO(F(2,24)=8,69; p=0.001; ηp2=0.42). Specifically, after the intervention, significant differences (p=0.008) were observedbetween the MICT group (0.36±0.10) and the CG (0.23±0.08). In fact, significant improvements in MFO were observed inMICT group (0.29±0.07 vs. 0.36±0.10; p=0.003), while the CG decreased MFO (0.27±0.10 vs. 0.22±0.08; p=0.016). Nosignificant effects were observed for blood glucose or HbA1c (p>0.05).CONCLUSION: A 12-week aerobic exercise program is effective for improving MFO and insulin sensitivity in adults withT2DM. In fact, MICT appears to be superior to HIIT, although no significant differences were found. However, more studiesare needed, since it seems that the benefits of HIIT and MICT are different depending on the adaptations that each training produces. Thus, HIIT could be more effective for improving cardiorespiratory fitness, although it depends on the HIITprotocol used, while for the improvement of glycemic parameters, both trainings are equally beneficial.Grants: 10.13039/501100011033PID2019-110063RA-I00, PID2020-120034RA-I00, and LI19/21IN-CO09.