When blood glucose levels increase, symptoms may include dry mouth, frequent urination, blurred vision and fatigue. When blood glucose levels are above 240 milligrams per deciliter (mg/dL), and a urine test shows the presence of ketones, a doctor should be contacted promptly. Ketones are a toxic byproduct created when the body can’t get energy from glucose.
It’s also common for blood glucose levels to be elevated without noticeable symptoms. Even when people feel fine, excess blood glucose is eroding the health of nerves, blood vessels, organs and other tissues. Over time, this can lead to kidney disease, loss of vision, nerve damage, heart attack and stroke.
Elevated blood glucose can be caused by many factors, including:
Changes in diet: Extra calories can increase blood glucose levels.
Changes in exercise habits: Exercise lowers blood glucose levels. Less exercise than usual can increase blood glucose levels.
Medications: The dose of diabetes medication and administration time may require occasional adjustments to keep blood glucose levels in the recommended range. Medications taken for other conditions also can affect blood glucose control.
Infections: Colds, the flu or bacterial infections can cause the body to produce hormones that increase blood glucose levels. High glucose levels can be caused by an infection that’s not apparent, or by a festering infection that has not been adequately treated.
Medical care or major medical problem: Surgery, heart attack, major emotional stress, an injury or a hospital stay can affect glucose-altering hormones.
Dawn effect: This abnormal early-morning increase in blood glucose levels is believed to be related to the release of hormones during sleep. Nighttime blood glucose monitoring may be needed to determine the cause of the morning elevation.
People with recurring instances of elevated blood glucose levels may be able to take steps to get levels back under control. But when levels are persistently high, even with appropriate diet and medications, it’s time to work with a doctor to identify changes needed for better management.
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