Glycaemic excursions during a standardised bout of hypoglycaemia-inducing physical activity and subsequent hypoglycaemia treatment in adult type 1 diabetes patients

Abstract

Background and aims: To characterize glucose dynamics during a standardized bout of hypoglycemia-inducing exercise and subsequent hypoglycemia treatment with oral ingestion of glucose in type 1 diabetes patients. Materials and methods: 10 male patients with type 1 diabetes (mean ±SD: age 34.4±3.9 years, diabetes duration 7.7±1,7 years, BMI 23.4±0.8 kg/m2, and HbA1c 7.4±0.62% (57±4.8 mmol/mol)) performed a standardized bout of cycling exercise using an electrically braked ergometer at a target heart rate (THR) of 50% of individual heart rate reserve, determined using the Karvonen equation. The exercise was terminated when hypoglycemia was reached, followed by immediate hypoglycemia treatment with oral ingestion of 20g glucose. Arterialized blood glucose (ABG) levels were monitored at 5-min intervals during exercise and for 60-min during recovery. A generalized additive model with smoothing spline was fitted to the ABG data against time to determine glucose dynamics during exercise and in recovery. Results: ThemeanABGvalue at the end of exercise was 3.63±1.00 mmol/l. During exercise, ABG decreased at a mean rate of 0.11±0.03 mmol/l.min-1 (minimum: 0.07, maximum: 0.17 mmol/l.min-1). During recovery, ABG increased at a mean rate of 0.13±0.05 mmol/l.min-1 (minimum: 0.06, maximum: 0.19 mmol/l.min-1). An example of glucose excursions during the study (Patients 1) is shown in Figure. Conclusion: We showed that at a defined level of hypoglycemicinducing steady-state exercise, glucose concentrations decrease on average by 1mmol/l every ten minutes, and is comparable to the rate of glucose restoration following oral ingestion of glucose. As also substantial variability was found more patients must be examined to analyse glucose changes with respect to the potential "speed group" characteristics.