The body breaks down carbohydrates that come from food like bread, cereals and pasta into glucose for energy, or stores them as fat. Insulin is a pancreatic hormone that helps glucose enter the body's cells. However, people with diabetes mellitus, often simply referred to as diabetes, have high blood sugar because their body no longer produce enough insulin. Without insulin, the excess glucose releases in the circulation instead of getting into the cells to be used for energy. Unexplained weight loss is typically associated with type 1 diabetes.
Type 1 Diabetes
People with type 1 diabetes that's undiagnosed or untreated can rapidly lose their body weight, according to the KidsHealth website. Type 1 diabetes is a form of diabetes mellitus that is characterized by a severe deficiency in insulin secretion resulting from the atrophy of the pancreas. People with type 1 diabetes can't convert sugar and starches found in foods into energy. Extra sugar either builds up in the bloodstream or passes out in the urine. People begin to lose weight because their muscle tissues don't get enough glucose, the main energy source for the body's functions.
Gluconeogenesis
Insulin also inhibits the breakdown of glycogen stored in muscle and liver, especially to glucose, known as glycogenolysis. It slows down the conversion of fat to triglycerides, free fatty acids and ketones, thereby stimulating fat storage. Furthermore, a decline in insulin promotes the protein and fat breakdown for glucose production in both the kidneys and the liver. The excess consumption of protein and fat in the body due to underactive insulin production leads to urinary ketone production and weight loss.
Hyperglycemia
Hyperglycemia or excess blood sugar concentration results when insufficient insulin production promotes gluconeogenesis, which in turn prevents the use and storage of circulating glucose. The kidneys cannot filter and reabsorb the excess glucose load, and the body flushes out excess sugar in the blood in urine. People with high blood sugar tend to urinate more frequently; this results in dehydration, a possible cause of weight loss.
