Hormonal disorders such as Cushing's syndrome, hyperthyroidism, and polycystic ovary syndrome (PCOS) can produce chronic high blood sugar.

Excess cortisol in Cushing's syndrome directly induces insulin resistance, while thyroid disorders alter metabolism and can impair glucose handling. PCOS is linked to insulin resistance and compensatory hyperinsulinemia, leading to elevated glucose. These conditions are repeatedly cited as underlying medical causes of hyperglycemia in people without diabetes.