Effect of Dapagliflozin on Cardiac Function and Metabolic and Hormonal Responses to Exercise

OBJECTIVE

This work aimed to investigate the effect of the SGLT2 inhibitor, dapagliflozin (DAPA), on cardiac function and the metabolic and hormonal response to moderate exercise in people with type 2 diabetes.

METHODS

This was a double-blind, placebo-controlled crossover study with a 4-week washout period. Nine participants were randomly assigned to receive either 4 weeks of DAPA or 4 weeks of placebo. After each treatment, they underwent an exercise protocol with 2 consecutive 10-minute stages at a constant load corresponding to 40% and 70% maximal oxygen consumption (VO2max), coupled with hormonal and metabolic analysis. A blinded transthoracic echocardiogram was performed 3 days later.

RESULTS

During the exercise protocol, glucose and lactate were lower (P < .0001 and P < .05, respectively) and β-hydroxybutyrate (BOBH) and growth hormone (GH) were higher (P < .0005 and P = .01) following DAPA treatment compared to placebo. There was a trend for lower insulin with DAPA. Adrenalin, noradrenalin, and glucagon were not different. Following DAPA participants demonstrated an increased mean peak diastolic mitral annular velocity (e') in comparison to placebo (P = .03). The indexed left atrial volume and right ventricular e" were reduced following DAPA compared with placebo (P = .045 and P = .042, respectively). Arterial stiffness was not different between treatments (DAPA 9.35 ± 0.60 m/s; placebo 9.07 ± 0.72 m/s).

CONCLUSION

During exercise, GH may be more important than catecholamines in driving the shift from glucose to fatty acid metabolism by SGLT2 inhibitors. The 4-week crossover design showed changes in cardiac function were rapid in onset and reversible.

The SGLT2 Inhibitor Dapagliflozin Increases the Oxidation of Ingested Fatty Acids to Ketones in Type 2 Diabetes

OBJECTIVE

To investigate the mechanism for increased ketogenesis following treatment with the SGLT2 inhibitor dapagliflozin in people with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The design was a double-blind, placebo-controlled, crossover study with a 4-week washout period. Participants received dapagliflozin or placebo in random order for 4 weeks. After each treatment, they ingested 30 mL of olive oil containing [U-13C]palmitate to measure ketogenesis, with blood sampling for 480 min. Stable isotopes of glucose and glycerol were infused to measure glucose flux and lipolysis, respectively, at 450-480 min.

RESULTS

Glucose excretion rate was higher and peripheral glucose uptake lower with dapagliflozin than placebo. Plasma β-hydroxybutyrate (BOHB) concentrations and [13C2]BOHB concentrations were higher and glucose concentrations lower with dapagliflozin than placebo. Nonesterified fatty acids (NEFAs) were higher with dapagliflozin at 300 and 420 min, but lipolysis at 450-480 min was not different. Triacylglycerol at all time points and endogenous glucose production rate at 450-480 min were not different between treatments.

CONCLUSIONS

The increase in ketone enrichment from the ingested palmitic acid tracer suggests that meal-derived fatty acids contribute to the increase in ketones during treatment with dapagliflozin. The increase in BOHB concentration with dapagliflozin occurred with only minimal changes in plasma NEFA concentration and no change in lipolysis. This finding suggests a metabolic switch to increase ketogenesis within the liver.

Metabolic Effects of an SGLT2 Inhibitor (Dapagliflozin) During a Period of Acute Insulin Withdrawal and Development of Ketoacidosis in People With Type 1 Diabetes

OBJECTIVE

To determine the effect of the sodium-glucose cotransporter 2 inhibitor dapagliflozin on glucose flux, lipolysis, and ketone body concentrations during insulin withdrawal in people with type 1 diabetes.

RESEARCH DESIGN AND METHODS

A double-blind, placebo-controlled crossover study with a 4-week washout period was performed in 12 people with type 1 diabetes using insulin pump therapy. Participants received dapagliflozin or placebo in random order for 7 days. Stable isotopes were infused to measure the glucose R_a, R_d, and lipolysis. At isotopic steady state, insulin was withdrawn, and the study was terminated after 600 min or earlier if blood glucose reached 18 mmol/L, bicarbonate <15 mmol/L, venous pH <7.35, or capillary ketones >5.0 mmol/L.

RESULTS

At baseline, glucose R_a was significantly higher for the dapagliflozin group than the placebo group. Following insulin withdrawal, plasma glucose concentrations at the end point were significantly lower with dapagliflozin than placebo and glucose R_d area under the curve (AUC)_{0-180 min} and β-hydroxybutyrate (BOHB) AUC_{0-180 min} were significantly higher. There was a small but significantly higher glycerol R_a (measure of lipolysis) AUC_{0-180 min} with dapagliflozin. Nonesterified fatty acid concentrations were not different between treatments. When divided by BMI >27 and <27 kg/m², basal glucose R_a, BOHB, and glycerol R_a AUC_{0-180 min} were significantly higher in the low-BMI group with dapagliflozin treatment versus the low-BMI group with placebo.

CONCLUSIONS

During insulin withdrawal, the increase in BOHB with dapagliflozin may be partially due to increased lipolysis. However, reduced renal excretion, reduced BOHB uptake by peripheral tissues, or a metabolic switch to increased ketogenesis within the liver may also play a role.