Diabetes can lead to acute (sudden and severe) and long-term complications — mainly due to extreme or prolonged high blood sugar levels. Acute diabetes complications Acute diabetes complications that can be life-threatening include: Hyperosmolar hyperglycemic state (HHS): This complication mainly affects people with Type 2 diabetes. It happens when your blood sugar levels are very high (over 600 milligrams per deciliter or mg/dL) for a long period, leading to severe dehydration and confusion. It requires immediate medical treatment. Diabetes-related ketoacidosis (DKA): This complication mainly affects people with Type 1 diabetes or undiagnosed T1D. It happens when your body doesn’t have enough insulin. If your body doesn’t have insulin, it can’t use glucose for energy, so it breaks down fat instead. This process eventually releases substances called ketones, which turn your blood acidic. This causes labored breathing, vomiting and loss of consciousness. DKA requires immediate medical treatment. Severe low blood sugar (hypoglycemia): Hypoglycemia happens when your blood sugar level drops below the range that’s healthy for you. Severe hypoglycemia is very low blood sugar. It mainly affects people with diabetes who use insulin. Signs include blurred or double vision, clumsiness, disorientation and seizures. It requires treatment with emergency glucagon and/or medical intervention. Long-term diabetes complications Blood glucose levels that remain high for too long can damage your body’s tissues and organs. This is mainly due to damage to your blood vessels and nerves, which support your body’s tissues. Cardiovascular (heart and blood vessel) issues are the most common type of long-term diabetes complication. They include: Coronary artery disease. Heart attack. Stroke. Atherosclerosis. edited