What causes high blood glucose (sugar)?

High blood glucose, or high blood sugar, is called hyperglycemia. It is when your blood glucose is above 180 mg/dL.

High blood glucose (hyperglycemia) may happen when you: 

• eat too much food

• take too little insulin or other diabetes medicines

• are less active than usual

• are stressed or more active than usual

This can happen slowly and may lead to a medical emergency if not taken care of.