Author(s): POON, E., HE, Y., YU, A., WONG, S., Institution: THE CHINESE UNIVERSITY OF HONG KONG, Country: HONG KONG, Abstract-ID: 1844

INTRODUCTION:
Prediabetes with abnormal glucoses level indicates a high risk of developing Type 2 diabetes, with high prevalence around the world. Lifestyle interventions such as diet and exercise are the key components of diabetes management. The low-carbohydrate diet (LCD) has been demonstrated to be effective in glycemic control by reducing the intake of carbohydrates, with less postprandial insulin secretion. High-intensity interval exercise (HIIE) was a popular strategy in improving cardiorespiratory fitness in a modern lifestyle characterized by prolonged sitting and an inactive lifestyle. This pilot study aimed to investigate the effects of HIIE combined with LCD for glycemic control and cardiovascular fitness in adults with prediabetes.
METHODS:
Thirty physically inactive adults with prediabetes, diagnosed according to the ADA criteria, were randomized (1:1:1) to HIIE (n = 10), LCD (n = 10), or combined group (COM) (n=10). Participants in the HIIE group performed 3 weekly sessions of 10 × 1-minute 80% HR max running with 1-minute active recovery periods of 50% HRmax. The LCD group received carbohydrate at least 10% but less than 26% and maintained their daily physical activity. The combined intervention consisted of both LCD and HIIE. All interventions lasted for 12 weeks. Venous blood was collected after 8 hours of fasting for assessing glycemic control indicators, such as HbA1c, fasting glucose, insulin, and HOMA-IR. All the outcomes were measured at baseline and post-test. VO2peak, which served as the gold standard for measuring cardiovascular fitness were assessed by the modified Bruce protocol. Generalized estimating equations model was used to examine the treatment effect on the outcomes. Statistical significance was set at p < 0.05.
RESULTS:
No significant group-by-time interaction effect was found for HbA1c (p = 0.697) and fasting glucose (p = 0.648). However, a significant main effect of time was observed in insulin (p = 0.004) and HOMA-IR (p = 0.022), suggesting an overall improvement in all groups. Notably, a significant group-by-time interaction effect was observed for VO2peak (p = 0.005). Compared with the LCD group, both the COM group (mean difference [95% confidence interval]: 4.27 mL/kg/min [1.49, 7.05], p = 0.003) and the HIIE group (5.37 mL/kg/min [2.98, 7.75], p < 0.001) showed greater improvement, with no significant difference between the COM group and the HIIE group (p = 0.517).
CONCLUSION:
These findings suggest that combined HIIE and LCD is an effective method for cardiorespiratory fitness in people with prediabetes. Although no significant difference was observed in HbA1c and fasting glucose, a significant time effect was found in insulin and HOMA-IR. This indicates all interventions may have potential benefits in glycemic control for adults with prediabetes.