Continuous glucose monitoring before and after exercise in patients with type 1 diabetes on CSII

Introduction: Exercise is associated with an increased risk of hypo- or hyperglycemic events and it is difficult to find the optimal balance between carbohydrate uptake, insulin dose, and the level and duration of exercise to avoid acute blood glucose deteriorations. The aim of our study was to monitor the impact of exercise on the glucose profile in the 21 hours thereafter in patients with type 1 diabetes managed by CSII before and after a 14 day moderate or intense training program.

Material and methods: Sixteen male patients (HbA1c 7.3±0.8% (mean±SD); age 39±11 years; BMI 26.0±2.7kg/m²) were enrolled in this single center, randomized, open-label study underwent exercise challenges (45min on a treadmill) before and after a 14 day moderate (Group A; n=8) or intense (Group B) training program. During the two in-house periods each patient participated in, glucose profiles were registered on the first day (Day 0) with standardized meals. On the second day (Day 1) patients performed glucose profiles were monitored before and for 21 hours after exercise (start at 11 a.m.) until the morning of Day 2 by means of a microdialysis glucose monitoring system (SCGM 1).

Results: The areas under the glucose profiles (calibrated to blood glucose) during the 21 hours after start of the exercise challenge were similar between group A and B, as well as pre- and posttraining (Group A: 2716±270 vs. 2726±211mg/dL*h and Group B: 2729±368 vs. 2846±456mg/dL*h). Continuous monitoring revealed numerous hypoglycemic events resulting in a trend towards lower prandial insulin doses. There were no between-group differences in terms of the overall number of hypoglycemic events and the events occurred constantly over time without any specific allocation to single patients.

Conclusions: Continuous glucose monitoring showed that under non-standardized conditions patients with type 1 diabetes on CSII respond to exercise challenges with no uniform response pattern, a not unexpected result. Also different levels of physical fitness have no impact on the outcome. CGM helps to detected hypo- and hyperglycemic events.