High blood sugar levels (hyperglycemia) occur when your blood sugar (also called glucose) is higher than your body needs to function normally. High blood sugar levels can cause both immediate and long-term problems.

Immediate problems

Diabetic ketoacidosis (DKA) is a life-threatening blood chemical (electrolyte) imbalance that develops in a person with diabetes when the cells do not get the sugar they need for energy. As a result, the body breaks down fat instead of glucose and produces and releases substances called ketones into the bloodstream.

People with type 1 diabetes and some people with type 2 diabetes have an increased risk for DKA if they do not take enough insulin, have a severe infection or other illness, or become severely dehydrated.

Symptoms of diabetic ketoacidosis include:

• Flushed, hot, dry skin.
• A strong, fruity breath odor.
• Loss of appetite, abdominal pain, and vomiting.
• Restlessness.
• Rapid, deep breathing.
• Confusion.
• Drowsiness or difficulty waking up. Young children may lack interest in their normal activities.

Severe diabetic ketoacidosis can cause difficulty breathing, brain swelling (cerebral edema), coma, or death. Prompt medical evaluation and treatment are needed if symptoms of diabetic ketoacidosis are present.

Treatment involves giving insulin and fluids through a vein and closely monitoring and replacing electrolytes.

Long-term complications

Your risk of complications increases if your blood sugar levels are often above your target level. Persistently high blood sugar can damage blood vessels and nerves.

• Damage to large blood vessels (macrovascular disease) can lead to a buildup of plaque, increasing your risk of coronary artery disease, heart attack, and stroke.
• Damage to small blood vessels (microvascular disease) can lead to loss of vision, kidney disease, and nerve problems throughout the body.
• Nerve damage (diabetic neuropathy) can decrease or completely block the movement of nerve impulses or messages through organs, legs, arms, and other parts of the body. Nerve damage can affect your internal organs and your ability to feel pain when you are injured.

If your episodes of high blood sugar levels are occurring more frequently, a visit to your doctor is needed.