Hyperglycemia is high blood glucose (sugar) levels. It is common in people with diabetes but can occur in people who have not been diagnosed with diabetes. It can develop slowly with no obvious ...

They include headache, nausea, vomiting, fever, a cough, and trouble breathing. Low blood sugar. This can cause you to have nausea and headache. You might faint or be sweaty and confused.

But elevated blood sugar can be a normal occurrence for most ... nausea and vomiting unintentional weight loss, fatigue, headache, dry mouth, fruity breath odor, a rapid heartbeat.