Symptoms of high glucose (blood sugar) may develop over a period of hours to days. When glucose levels are slightly elevated, the patient may have mild symptoms or no symptoms at all. As glucose levels continue to increase, some people can develop more intense symptoms. Other individuals may show no symptoms until their glucose levels are very high because their bodies adjust to the increase.

Common symptoms of hyperglycemia include:

• Polyuria (excessive urination)
• Polydipsia (excessive thirst)
• Polyphagia (excessive hunger)
• Weakness
• Fatigue, exhaustion or lethargy
• Blurred vision

Other signs and symptoms include:

• Sweet, fruity-smelling breath
• Drowsiness
• Loss of appetite
• Stomach pain
• Nausea or vomiting
• Sudden unexplained weight loss
• Heavy labored breathing (Kussmaul breathing)
• Dehydration
• Dry mouth or skin
• Slow-healing sores
• Frequent infections, such as yeast infections or urinary tract infections
• Difficulty concentrating
• Headaches
• Unconsciousness/coma

People with diabetes can avoid the advanced symptoms of hyperglycemia by checking their glucose levels often with a glucose meter and then treating high blood glucose early, according to their physician’s recommendations.