Exercise intensities and metabolic health: Targeting blood glucose, insulin, and C-peptide levels in adults with prediabetes in the postprandial state

Objective: Exercise improves postprandial glycaemia and insulin sensitivity in individuals with prediabetes, but the optimal intensity for this metabolic regulation remains unclear. The current study aims to explore the impact of various exercise intensities on metabolic markers in pre- diabetic individuals to identify the optimal intensity for improving these indicators. Methods: In this crossover study, 25 prediabetic individuals participated in exercise sessions at 50 %, 60 %, 70 %, and 80 % intensities of their predicted maximum heart rate using a treadmill. Each session lasted for 30 min, including a 5-min warm-up and a 5-min cool-down period. Blood samples were collected at four distinct time points: during fasting, immediately before exercise, and 30 and 60 min post-exercise. These samples were analyzed for glucose, insulin, and C-peptide levels. The effects of exercise intensity on these parameters were evaluated using repeated measures ANOVA, with post hoc tests conducted to determine specific differences between the intensities. Results: The participants had an average age of 34.88 years, a mean height of 170 cm, and a BMI of 30.34 kg/m2. A significant reduction in insulin and glucose levels postexercise was observed at 70 % intensity (p < 0.001). Despite high fasting blood glucose levels (110-115 mg/dL), significant reductions were noted at 30 and 60 min post-exercise (p < 0.001). Insulin levels approached near baseline at 70 % intensity, from fasting (26.74 f 20.83) to 60 min post-exercise (28.47 f 20.79), indicating a positive response at this intensity. C-peptide levels also showed significant changes, with the 70 % intensity exercise bringing them closest to fasting levels by 60 min post-exercise. Conclusion: This study highlights the importance of exercise intensities in enhancing metabolic parameters in prediabetic individuals. Specifically, 70 % of the predicted maximum heart rate was beneficial, optimizing insulin sensitivity and potentially reducing the risk of progressing from prediabetes to diabetes.