Hyperglycemia, or high blood glucose (sugar), is a serious health problem for those with diabetes. Hyperglycemia develops when there is too much sugar in the blood.
In people with diabetes, there are two specific types of hyperglycemia that occur:
Fasting hyperglycemia is defined as a blood sugar greater than 90-130 mg/dL (milligrams per deciliter) after fasting for at least 8 hours.
Postprandial or after-meal hyperglycemia is defined as a blood sugar usually greater than 180 mg/dL. In people without diabetes postprandial or post-meal sugars rarely go over 140 mg/dL but occasionally, after a large meal, a 1-2 hour post-meal glucose level can reach 180 mg/dL. Consistently elevated high post-meal glucose levels can be an indicator that a person is at high risk for developing type 2 diabetes.
When a person with diabetes has hyperglycemia frequently or for long periods of time as indicated by a high HbA1c blood test, damage to nerves, blood vessels and other body organs can occur.
Hyperglycemia can also lead to more serious conditions, includingketoacidosis - mostly in people with type 1 diabetes - and hyperglycemic hyperosmolar nonketotic syndrome (HHNS) in people with type 2 diabetes or in people at risk for type 2 diabetes.
It's important to treat the symptoms of hyperglycemia promptly to prevent complications from diabetes.
Temporary hyperglycemia is often benign and asymptomatic. Blood glucose levels can rise well above normal for significant periods without producing any permanent effects or symptoms.
However, chronic hyperglycemia at levels more than slightly above normal can produce a very wide variety of serious complications over a period of years, including kidney damage, neurological damage, cardiovascular damage, damage to the retina etc.
In diabetes mellitus (by far the most common cause of chronic hyperglycemia), treatment aims at maintaining blood glucose at a level as close to normal as possible, in order to avoid these serious long-term complications.
Acute hyperglycemia involving glucose levels that are extremely high is a medical emergency and can rapidly produce serious complications (such as fluid loss through osmotic diuresis). It is most often seen in persons who have uncontrolled insulin-dependent diabetes.
The following symptoms may be associated with acute or chronic hyperglycemia, with the first three composing the classic hyperglycemic triad:
- Polyphagia - frequent hunger, especially pronounced hunger.
- Polydipsia - frequent thirst, especially excessive thirst.
- Polyuria - frequent urination.
- Blurred vision.
- Fatigue (sleepiness).
- Weight loss.
- Poor wound healing (cuts, scrapes, etc.).
- Dry mouth.
- Dry or itchy skin.
- Tingling in feet or heels.
- Erectile dysfunction.
- Recurrent infections, external ear infections (swimmer's ear).
- Cardiac arrhythmia.
Frequent hunger without other symptoms can also indicate that blood sugar levels are too low. This may occur when people who have diabetes take too much oral hypoglycemic medication or insulin for the amount of food they eat.
The resulting drop in blood sugar level to below the normal range prompts a hunger response. This hunger is not usually as pronounced as in Type I diabetes, especially the juvenile onset form, but it makes the prescription of oral hypoglycemic medication difficult to manage.
Polydipsia and polyuria occur when blood glucose levels rise high enough to result in excretion of excess glucose via the kidneys (glycosuria), producing osmotic diuresis.
Symptoms of Diabetic Ketoacidosis may include:
- Kussmaul hyperventilation: deep, rapid breathing.
- Confusion or a decreased level of consciousness.
- Dehydration due to glycosuria and osmotic diuresis.
- Acute hunger and/or thirst.
- 'Fruity' smelling breath odor.
- Impairment of cognitive function, along with increased sadness and anxiety.
If you have diabetes and have any of the early signs of hyperglycemia, be sure to test your blood glucose several times. You will need to have a record of several blood glucose readings before you call your health care provider.
He or she may recommend the following changes:
- Drink more water. Water helps remove the excess glucose from your urine and helps you avoid dehydration.
- Exercise more. Exercise will help to lower your blood glucose. Caution: If you have type 1 diabetes and your blood glucose is over 240 mg/dL, you need to check your urine for ketones. When you have ketones, do NOT exercise. If you have type 2 diabetes and your blood glucose is over 300 mg/dL, even without ketones, do NOT exercise.
- Change your eating habits. You may need to meet with the dietitian to change the amount and types of foods you are eating.
- Change your medications. Your health care provider may change the amount, timing, or type of diabetes medications you take. Do not make adjustments in your diabetes medications without first talking with your health care provider.
If you have type 1 diabetes and your blood glucose is more than 250 mg/dL, your doctor may want you to test your urine or blood for ketones.
Call your doctor if your blood glucose is consistently greater than 180 mg/dL 1-2 hours after a meal or if you have two consecutive readings greater than 300 mg/dL.