G6PC1 and obesity due to melanocortin 4 receptor deficiency: Moreover, no differences or a lower expression of genes like phosphoenolpyruvate carboxykinase or glucose-6-phosphatase, catalytic (G6PC) were found in mice treated with a high-fat diet vs. controls or in humans with obesity undergoing bariatric surgery, despite fasting hyperglycemia and increased hepatic glucose fluxes.44