Polyphagia is a common sign of diabetes. This is because diabetes is characterized by the body’s inability to produce (in type 1 diabetes) or properly use (in type 2 diabetes) insulin. Insulin is a hormone produced by the pancreas to regulate glucose (blood sugar).

When insulin is lacking, glucose builds up in the bloodstream instead of entering the cells. The body is unable to use this glucose for energy. In other words, lack of insulin causes the cells to enter a state of starvation even though there is an excess of sugar in the blood. This condition, which can affect all types of diabetes, is called hyperglycemia. Other symptoms of hyperglycemia due to diabetes include polydipsia (excessive thirst) and polyuria (excessive urination).

When people with diabetes experience hyperglycemia, they may feel as though they are starving, despite overeating. This voracious hunger does not diminish until blood glucose finally enters the cells. In type 1 diabetes, the body, which normally burns glucose for fuel, may begin to burn fat instead. This is why many polyphagic individuals with type 1 diabetes report unexplained weight loss despite consuming an inordinate number of calories.

Type 2 diabetes is associated with a condition called insulin resistance. The body produces enough insulin to meet its needs but is unable to detect or use the hormone properly. The body is therefore unable to transfer glucose from the bloodstream to the cells, and hyperglycemia ensues. Many people with type 2 diabetes and polyphagia gain weight because insulin resistance and overeating result in excess production of insulin. This hyperinsulinemia, in turn, results in the storage of excess food, which increases body fat.

Individuals with other forms of diabetes, including gestational diabetes (diabetes that occurs during pregnancy), latent autoimmune diabetes of adulthood (LADA), maturity-onset diabetes of the young (MODY) and secondary diabetes, may also experience polyphagia. Sometimes people with prediabetes may have polyphagia.

Other diabetic conditions that can trigger polyphagia include low glucose (hypoglycemia), which causes the autonomic nervous system to produce symptoms such as hunger and shakiness, and diabetic ketoacidosis, in which the body burns fats rather than glucose for energy.