A blood sugar of 33 mmol/l is dangerous and may be combined with acute complications of diabetes such as diabetic ketoacidosis and hyperosmolar hyperglycemic coma. The common acute complications of diabetes are diabetic ketoacidosis and hyperosmolar hyperosmolar state. Ketoacidosis will have diabetic polyphagia, polydipsia, polyuria, weight loss, and also gastrointestinal symptoms such as nausea and vomiting, abdominal pain, and even serious manifestations such as dehydration, circulatory collapse, coma, and shock. A hyperglycemic hypertonic state can lead to severe dehydration and eventually to impaired consciousness or even coma. Long-term uncontrolled diabetes can also lead to complications such as diabetic retinopathy, diabetic nephropathy, atherosclerosis, diabetic neuropathy, diabetic skin infections, diabetic maculopathy and diabetic foot. A blood sugar of 33mmol/l is dangerous. Patients should go to the hospital in time and be treated under the guidance of a doctor to prevent serious complications and even death.