Effects of exercise and metformin on the prevention of glucose intolerance: a comparative study

The effect of metformin on glucose metabolism in patients receiving glucocorticoids

Glucocorticoids have powerful anti-inflammatory and immunomodulatory effects, but chronic use of these drugs can cause hyperglycemia, type 2 diabetes mellitus, hepatic steatosis, obesity, and other complications due to their metabolic actions. Metformin is a widely used drug for the treatment of type 2 diabetes mellitus with a known ability to lower blood glucose levels. This review focuses on metformin's actions on glucose metabolism and its potential use as a drug to limit the metabolic side effects of glucocorticoid treatment. Available data suggest that metformin inhibits complex I of the mitochondrial electron transport chain, crucial gluconeogenic enzymes, and fatty acid synthesis that leads to a significant improvement in glucose tolerance and maintenance of insulin sensitivity during glucocorticoid treatment. Three small randomized control trials have demonstrated that metformin can limit changes in glucose metabolism during treatment with prednisone. These studies reveal a promising potential for metformin use as a therapeutic agent to reduce glucocorticoid-induced hyperglycemia and improve patient outcomes.

Coadministration of sitagliptin or metformin has no major impact on the adverse metabolic outcomes induced by dexamethasone treatment in rats

AIMS

Glucocorticoids (GC) in excess cause glucose intolerance and dyslipidemia due to their diabetogenic actions. Conceptually, antidiabetic drugs should attenuate these side effects. Thus, we evaluated whether the coadministration of metformin or sitagliptin (or both) with dexamethasone could attenuate GC-induced adverse effects on metabolism.

MATERIALS AND METHODS

Adult male rats were treated for 5 consecutive days with dexamethasone (1 mg/kg, body mass (bm), intraperitoneally). Additional groups were coadministered with metformin (300 mg/kg, bm, by oral gavage (og)) or sitagliptin (20 mg/kg, bm, og) or with both compounds in combination. The day after the last treatments, rats were submitted to glucose tolerance tests, pyruvate tolerance test, and euthanized for biometric, biochemical, morphologic, and molecular analyses.

KEY FINDINGS

Dexamethasone treatment resulted in reduced body mass and food intake, increased blood glucose and plasma insulin, dyslipidemia, glucose intolerance, pyruvate intolerance, and increased hepatic content of glycogen and fat. Sitagliptin coadministration improved glucose tolerance compared with the control group, an effect paralleled with higher levels of active GLP-1 during an oral GTT. Overall, sitagliptin or metformin coadministration did not prevent any of the dexamethasone-induced metabolic disturbances.

SIGNIFICANCE

Coadministration of sitagliptin or metformin result in no major improvement of glucose and lipid metabolism altered by dexamethasone treatment in male adult rats.

Influence of the physical exercise on decrease in the gastric emptying and alter appetite and food behavior in rats dexamethasone-treatment

The chronic use of Dexamethasone (Dex) induced hyperglycemia and insulin resistance. On the other hand, physical exercise attenuates the symptoms induced by Dex in many physiological systems. However, the effect of the exercise on the changes in gastric motility induced by dexamethasone remains unknown. We hypothesized that low-intensity aerobic exercise modulates the metabolic effects induced by Dex-treatment by modifying the gastrointestinal function and feeding behavior in rats. Male rats were distributed into the following groups: Control (Ctrl), Dex (1.0 mg/kg, i.p.), Exercise (Ctrl + Exercise 5%) and (Dex1.0 + Exercise 5%). The exercise protocol was swimming for 5 consecutive days. We assessed the murinometric and nutritional indices, food intake, blood glucose by (ipGTT) and the gastric emptying rate of a liquid test meal were assessed in all rats. We observed a significant decrease (p < .05) in the gastric emptying in Dex1.0 group in relation to Ctrl group. The exercise prevented decrease in the gastric emptying (p < .05) in Dex1.0 + EX5% group when compared with Dex1.0 groups. The Dex1.0 group induced a significantly increase (p < .05) in glycaemia vs Ctrl group. The hyperglycemia was improving (p < .05) in the Dex1.0 + Ex5% compared with Dex1.0 groups. We observed a positive correlation (p < .05, and r = 0.7065) between gastric retention vs glycaemia in the Dex1.0 groups. The Dex1.0 reduced (p < .05) the body weight and altered body composition, promoting hypophagia. IL-6 increased (p < .05) at gastric fundus in Ex5% compared with Ctrl groups. In conclusion, the use of Dex1.0 decreases gastric emptying, promotes hyperglycemia and modifies feeding behavior. The low-intensity exercise prevents hyperglycemia, thus improving gastric dysmotility without improving the anthropometric parameters.