The Acute Effects of Exercise Intensity on Blood Glucose Levels in Type 1 Diabetics

Abstract

For individuals with Type 1 diabetes mellitus (T1DM), regular physical activity is a fundamental strategy in the management of glycemic control. Previous studies have shown that continuous, moderate-intensity exercise in individuals with T1DM decreases blood glucose concentrations, often resulting in hypoglycemia, whereas vigorous-intensity exercise can increase blood glucose, impacting the risk of hyperglycemia. Sprint interval training (SIT), characterized by brief, all-out bursts of supramaximal exercise, has been shown to improve indices of cardiometabolic health, despite a minimal time commitment. However, the effects of low volume SIT on individuals with T1DM is largely unknown. PURPOSE: to contrast the acute effects of exercise intensity on blood glucose levels in Type 1 diabetics. METHODS: Four recreationally active college- age students with T1DM, completed a treadmill test to determine maximal aerobic speed (MAS), and performed each of the following 20-min treadmill-based protocols: 1) Moderate-intensity continuous training (MICT): 5-min warm-up (WU), 10 minutes at 70% MAS, 5-min cool-down (CD); 2) high-intensity interval training (HIIT): 5-min WU, 1-min at 90% MAS, 1-min at 30% MAS repeated 5 times, 5-min CD; 3) SIT: 5-min WU, 30-sec at 120% MAS, 2-min, 50-sec at 30% MAS repeated 3 times, 5-min CD. Blood glucose was monitored via glucometer every 5-min during exercise and for 45-min after. RESULTS: A statistically significant decline in blood glucose was observed in both the MICT and HIIT conditions (p <0.001, respectively) but not in the SIT condition (p = 0.696). From baseline to the 45-min mark, blood glucose decreased by 27% in both the MICT (180 ± 27 to 132 ± 39) and HIIT (183 ± 29 to 132 ± 15) protocols, but only 11% in the SIT (193 ± 41 to 165 ± 70) protocol. CONCLUSIONS: The results of this study provide initial proof-of-concept that a low volume SIT protocol can maintain target blood glucose levels while exercising in individuals with T1DM.