The main acute complications in type 2 diabetes mellitus (DM2) are the diabetic ketoacidosis (CAD) and hyperosmolar hyperglycemic status (EHH). These conditions are due to an absolute or relative insulin defi ciency leading to volemia depletion with or without acid-basic equilibrium abnormalities. The main triggering factors include the onset of diabetes, oral or insulin treatment withdrawal, cardiovascular diseases, food transgressions, infections, emotional stress and drugs. The early diagnosis and treatment may prevent lethal complications. This review is focused on published literature and clinical guidelines from the Endocrinology Unit of the Autonomous Institute University Hospital of the Andes, Merida, Venezuela. It includes the diagnosis, treatment, resolution and complications criteria.