Long-acting dual amylin and calcitonin receptor agonists (DACRAs) are novel candidates for the treatment of type 2 diabetes and obesity due to their beneficial effects on body weight, glucose control, and insulin action. However, how the metabolic benefits are maintained after long-lasting treatment is unknown. This study investigates the long-term anti-obesity and anti-diabetic treatment efficacy of the DACRA KBP-336 alone and combined with the GLP-1 analog semaglutide. Zucker diabetic Sprague Dawley (ZDSD) rats with obesity and diabetes received KBP-336 (4.5 nmol/kg Q3D), semaglutide (50 nmol/kg Q3D), or the combination for 7 months, and the treatment impact on body weight, food intake, glucose control, and insulin action was evaluated. Furthermore, serum levels of the cardiac fibrosis biomarker endotrophin were evaluated. KBP-336, semaglutide and the combination lowered body weight significantly compared to the vehicle, with the combination inducing a larger and more sustained weight loss than either monotherapy. All treatments resulted in reduced fasting blood glucose levels and HbA1c levels, and improved glucose tolerance compared to vehicle-treated rats. Further, all treatments protected against lost insulin secretory capacity and improved insulin action. Serum levels of endotrophin were significantly lowered by KBP-336 compared to vehicle. This study shows the benefit of combining KBP-336 and semaglutide to obtain significant and sustained weight loss and improved glucose control. Further, KBP-336-driven reductions in circulating endotrophin indicate a clear reduction in the risk of complications. Altogether, KBP-336 is a promising candidate for the treatment of obesity and type 2 diabetes both alone and in combination with GLP-1 analogs.