When there isn’t enough insulin or cells stop responding to insulin, too much blood sugar stays in the bloodstream. When glucose doesn’t move into the cells, the body thinks it is starving and finds a way to compensate. It creates energy by burning fat and muscle at a fast pace. This is what leads to unexplained weight loss in people with diabetes.

Most of the time, this occurs in cases of Type 1 diabetes, although Type 2 diabetes can cause unexplained weight loss, too. This type of unexplained weight loss could be a sign of undiagnosed diabetes. It could also stem from a host of other conditions, including thyroid issues, celiac disease, Crohn’s disease, cancer, and more. 

If blood sugars are high in a diabetes patient, it can make them urinate frequently, and this results in dehydration as a possible cause of weight loss. As sugar leaves your body, so do calories and weight loss may occur. Similarly, high blood sugars can also result in muscle breakdown and hence weight loss. 

On the flip side, people who have diabetes may experience weight gain as a side effect of insulin therapy. Although insulin help regulates their glucose levels, it also promotes fat storage in the body.