An endocrine disease can be associated with glucose intolerance or diabetes mellitus, and the latter can falsely be considered as type 2 diabetes. Glycemic imbalance can be a direct or indirect consequence of excessive hormone production. Endocrine diseases such as acromegaly, Cushing's syndrome and pheochromocytoma can increase glucose production and cause insulin resistance. Hyperthyroidism, hyperaldosteronism, glucagonoma and somatostatinoma lead to hyperglycemia by other physiopathological mechanisms detailed in this article. When a clinical picture suggests an endocrine disease, several analyses need to be done in order to avoid treatment escalation of diabetes.