A hyperosmolar hyperglycemic state (HHS) develops when a person with type 2 diabetes has very high blood sugar—usually 34.0 millimoles per litre (mmol/L) or more. Sometimes this condition is the first time a person learns that he or she has type 2 diabetes.

A hyperosmolar hyperglycemic state can develop when a person is very sick and/or dehydrated, such as from the flu, a severe infection, a heart attack, or water pills (diuretics). If the person does not drink enough liquids, he or she may become confused. Older people are at increased risk for developing a hyperosmolar state.

Symptoms of a hyperosmolar hyperglycemic state include:

• Increased urination for several days.
• Dehydration, which develops because the person doesn't drink enough liquids.
• A change in alertness from generalized fatigue to stupor, coma, or seizures. These changes may be mistaken for a stroke or mental illness.

Hyperosmolar hyperglycemic state is treated in a hospital with insulin to reduce the blood sugar level and extra fluids through a vein (IV) to replace the lost fluids.

The best way to prevent a hyperosmolar hyperglycemic state is to treat high blood sugar levels early and drink enough liquids.