Dapagliflozin in Physical Exercise in Type 1 Diabetes

Overview

Inhibitors of sodium-dependent glucose-transporter 2 (SGLT-2 inhibitors, including dapagliflozin) inhibit glucose reabsorption in renal tubular cells, hereby increasing glycosuria in the hyperglycemic state. Its mechanisms of action are independent of insulin, which makes SGLT-2 inhibitors a potential adjunct to insulin in type 1 diabetes mellitus (T1DM). However, a higher risk for diabetic ketoacidosis (DKA) was reported in patients with T1DM taking SGLT-2 inhibitors. DKA depends on an accumulation of ketone bodies in the blood stream, which equals an accumulation of acids that lead to acidosis. The underlying mechanisms of this observation are unknown. Ketone body production depends on the molar ratio of glucagon to insulin, with insulin suppressing but glucagon stimulating ketone body production. This translates into higher production during relative insulin deficiency, carbohydrate deficiency, and prolonged fasting, which occurs during sickness but also physical exercise. Physical exercise is a recommended cornerstone in the treatment of T1DM and current treatment guidelines recommend both, reductions of insulin doses and ingestion of additional carbohydrates to avoid hypoglycemic events. These adaptions might increase relative insulin deficiency, hyperglycemia and glycaemic variability, which might in turn promote ketone body production. The addition of SGLT-2 inhibitors further may promote ketogenesis even though there are reports of SGLT-2 inhibitors increase Glucagon-like-peptide-1 (GLP-1) in patients with T1DM. GLP-1 is a suppressor of glucagon secretion. In summary, knowledge about the effects of SGLT-2 inhibition on ketone body production is scarce, especially during exercise in patients with T1DM. The study seeks to illustrate the effect of SGLT-2 inhibition on glycemic variability and ketone body production during and after recreational exercise in patients with T1DM. The results of study 2 will provide the basis for future studies investigating the underlying mechanisms of potentially modified ketone body production during and after exercise under SGLT-2 inhibition.