Delayed Nocturnal Hypoglycemia In Type 1 Diabetic Patients: Effect Of Two Different Exercise Modalities

Abstract: Exercise is a cornerstone of diabetes management as it aids in glycemic control in type 1 diabetic patients (DMT1). The type of exercise is important in determining the propensity to experience hypoglycaemia. PURPOSE: To assess, by continuous glucose monitoring (CGM), the glucose variability and the possible hypoglycemic episodes before, during and in the following 24 hours after a session of two different types of exercise. METHODS: Eight healthy, physically active, non-trained, male volunteers with well-controlled DMT1 were studied [age 34±7 yr, body mass index (BMI) 24.0±2.2 kg/m2, HbA1c 7.14±0.6, insulin dosage 0.6±0.2 U/kg/day, VO2max 33.7± 6.1 ml·kg-1·min-1, duration of diabetes 14.3±8yr (mean±SD)]. They underwent to 30 min. of both intermittent high intensity exercise (IHE) and moderate intensity exercise (MOD) in random order. Expired air was recorded during the exercise, while metabolic and hormonal determinations were performed before and for 120 min after exercises. CGM system and activity monitor were applied for the subsequent 19 hours. RESULTS: Blood glucose declined during both type of exercise. At 150 min following the start of exercise, plasma glucose tended to be higher, although not significantly, after IHE. No changes were observed in plasma insulin concentration. A significant increase of norepinephrine concentration was noticed during IHE respect to MOD (peak values: 1016.3±154 vs 680.0±84.5pg/mL; p<0.05) while no differences were observed in epinephrine levels. During nighttime glucose levels were significantly lower after IHE than those observed after MOD exercise (147±17 vs 225±31mg/dl at 3:00AM, p<0.05). Moreover, the number of hypoglycemic episodes after IHE was significantly higher than that observed after MOD (2 in MOD vs 7 and IHE). CONCLUSIONS: We demonstrate a previously unrecognized phenomenon: despite slightly higher plasma glucose values in the early post-exercise, IHE is associated with a higher risk of delayed nocturnal hypoglycemia respect to MOD. These data suggest that CGM can be a useful approach in Type 1 diabetic patients who undergo to an exercise program.