Updated March 13, 2015
Published April 2, 2007 by Laura Hieronymus, MSEd, APRN, BC-ADM, CDE, and Belinda O’Connell, MS, RD, CDE
When you were diagnosed with diabetes, your doctor probably told you that your blood glucose levels were too high. Indeed, high blood glucose, or hyperglycemia, is the hallmark of diabetes. Regardless of your knowledge of diabetes at that time, you may have wondered what the significance of high blood glucose levels was for you. The answer is that hyperglycemia is linked to the development of long-term diabetes complications, which include nephropathy (kidney disease), retinopathy (eye disease), neuropathy (nerve damage), foot and skin problems, heart and blood vessel disease, and tooth and gum disease. That’s why individual treatment plans for people with diabetes focus on preventing hyperglycemia and keeping blood glucose levels as close to the normal range as possible. Keeping blood glucose levels close to normal requires learning how to balance food intake, physical activity, and the effects of any diabetes medicines your doctor may prescribe to lower your blood glucose level. For some people, the balancing act also involves learning to avoid hypoglycemia, or low blood glucose.
Blood glucose goals
In healthy people who don’t have diabetes, blood glucose levels typically run in the range of 65–110 mg/dl and may rise to 120–140 mg/dl one to two hours after eating. A diagnosis of diabetes is made when a person’s fasting blood glucose level is above 126 mg/dl on two separate occasions or when a person has symptoms of diabetes (such as excessive thirst and urination) and his nonfasting blood glucose level is greater than 200 mg/dl on two separate occasions.
Until several years ago, a diagnosis of prediabetes, a condition in which blood glucose levels are high but not high enough for a diagnosis of diabetes, was made when a person’s fasting blood glucose level was between 110 mg/dl and 126 mg/dl. In 2004, an international expert committee on diabetes recommended diagnosing prediabetes when a person’s fasting blood glucose level is 100 mg/dl, and the American Diabetes Association (ADA) has adopted this recommendation.
On the basis of research showing that maintaining near-normal blood glucose levels significantly reduces the risk of diabetes-related complications, both the ADA and the American College of Endocrinology (ACE) have established recommended goals for blood glucose control for most adults with diabetes. These goals may be modified for certain populations. For example, the goals for blood glucose control are typically lower for women with diabetes who are pregnant. For children and the elderly, particularly those who take insulin as part of their treatment plan, the goals may be higher for safety reasons. Because each person’s situation is different, it is important to work with your diabetes care team to set individualized blood glucose goals that are right for you.
Two significant studies that paved the way toward today’s blood glucose goals are the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS). Both demonstrated that the closer blood glucose levels are kept to normal, the less likely a person with diabetes is to develop complications.
DCCT. The DCCT followed 1,441 people with Type 1 diabetes for an average of about seven years. The subjects were divided into two groups: the “conventional” treatment group, and the “intensive” treatment group. While the group that was treated intensively did not achieve normal, nondiabetic blood glucose levels, they were able to achieve an average blood glucose level of 155 mg/dl. The conventionally treated group’s blood glucose level averaged 231 mg/dl. During the study period, the intensively treated group had an approximate 60% reduction of risk for neuropathy, nephropathy, and retinopathy. Intensive therapy not only delayed the onset of complications but it also slowed the progression of complications in those who already had them, regardless of age, sex, or duration of diabetes.
UKPDS. The UKPDS examined the effects of varying levels of blood glucose control in 5,102 individuals with Type 2 diabetes, who were followed for an average of 10 years. The intensively treated group achieved an average blood glucose level of 150 mg/dl, while the conventionally treated group’s average blood glucose levels were approximately 177 mg/dl. In this study, intensive blood glucose control resulted in a 25% reduction of risk for neuropathy, nephropathy, and retinopathy. Furthermore, the study concluded that for every percentage drop in glycosylated hemoglobin (HbA1c, a measure of long-term blood glucose control), there was a 35% reduction in the risk of complications.
As these studies make clear, it is worth the effort to take steps to control your blood glucose, but how do you do that? And how do you know if you have hyperglycemia in the first place?
The best way to identify hyperglycemia is to routinely monitor your blood glucose levels on a schedule determined by you and your health-care team and to get regular HbA1c tests, also on a schedule agreed on by you and your health-care team (usually two to four times a year). That’s because hyperglycemia may not cause any symptoms until blood glucose levels are much higher than recommended ranges. So just because you feel OK doesn’t necessarily mean your blood glucose level is well controlled.
When they do occur, symptoms of hyperglycemia may include frequent urination, hunger, dry mouth, thirst, blurred vision, numbness or tingling in the hands and feet, decreased sexual function, and fatigue. All of these symptoms should prompt immediate action, starting with checking your blood glucose level with your meter to see if it’s high. What you do next will depend in large part on how you normally treat your diabetes.
Because regimens for treating diabetes vary widely, there is no “one size fits all” plan for treating hyperglycemia. If you currently treat your Type 2 diabetes with meal planning and exercise, for example, you may be instructed to add several minutes to your usual exercise routine or to decrease your carbohydrate intake at your next meal when your blood glucose level is high. If you have Type 1 diabetes and use an insulin pump, you may be instructed to take more insulin (possibly via syringe or insulin pen), and your diabetes care team will teach you how to determine how much insulin to take based on your blood glucose level. It’s extremely important to work with your diabetes care team to develop an individualized hyperglycemia action plan for you.
No matter what type of diabetes you have or how you treat it, part of your hyperglycemia action plan will likely be more frequent blood glucose monitoring, at least temporarily, to help determine why your blood glucose is high and what you can do to avoid future episodes of hyperglycemia. Indeed, prevention is the best and most effective way to treat hyperglycemia.
Many variables, some of which are described here, can upset the delicate balance that is necessary for the best diabetes control. When dealing with diabetes, you will inevitably experience some if not all of the following issues.
If you eat more food than is balanced with your physical activity and, in some cases, diabetes medicines, your blood glucose level may rise above your goal range. Carbohydrate-containing foods directly affect your blood glucose level after eating, so reviewing the amount of carbohydrate in your meals and snacks may be helpful in determining the cause of hyperglycemia. Carefully reading nutritional labels on food products and measuring portions will help you to meet your carbohydrate goals. On packaged foods, the total carbohydrate per serving is listed on the Nutrition Facts panel of the label. Meals that are high in fat may contribute to prolonged elevations in blood glucose after eating. Working with a registered dietitian, preferably one with experience in diabetes management, can be helpful in fine-tuning your meal-planning and carbohydrate-counting skills.
If you experience hyperglycemia in spite of sticking to your meal plan most of the time, it may indicate that the medicines included in your diabetes regimen need adjusting. If this is the case, undereating will not help lower your blood glucose level; you should consult your physician.
Exercise usually lowers blood glucose levels because it improves your cells’ sensitivity to insulin and helps cells burn glucose for energy. But if your blood glucose level is high before you exercise, it may go higher during exercise. When you begin exercising, your liver pumps out extra glucose to fuel your muscles. If your body has too little insulin circulating in the bloodstream to allow the cells to use the extra glucose, your blood glucose level will rise. High blood glucose levels with exercise can also be a sign that you are working too hard and your body is under stress. If this is the case, you need to slow down and gradually work up to a more strenuous level of activity.
For people with Type 1 diabetes, the ADA advises avoiding exercise if fasting blood glucose levels are above 250 mg/dl and ketones are present in blood or urine; caution should be used if blood glucose levels are above 300 mg/dl and no ketones are present. People with Type 2 diabetes may wish to consult their diabetes care team for individual recommendations.
Insulin and diabetes pills are taken to lower blood glucose levels, so forgetting a dose, taking the wrong dose, or taking the right dose at the wrong time can contribute to hyperglycemia. If you develop hyperglycemia, here are some questions you may want to ask yourself regarding your medicine(s):
– Did you take the proper dose? Double-check to make sure your dose was accurate. Sometimes different doses of the same oral diabetes medicine or insulin are prescribed at different times of day. Did the correct dose coincide with the correct time?
– Could you have forgotten to take your medicine? It is only human to forget things from time to time, even parts of your daily routine. If you think you may have forgotten to take your medicine, ask yourself if you specifically remember taking it. Can you backtrack to determine if you took it? If you seem to forget to take your medicine regularly, look for patterns: Are you having difficulty remembering a certain dose? If so, you may want to brainstorm some ways to remember it, such as setting an alarm for dose time or posting a note to yourself in a place you can’t miss. Insulin pumps generally have a review screen that allows you to see whether doses have been delivered.
– Has the medicine expired? Check the expiration date on your medicine to see if it is still good. Most pills have a long shelf life, but insulin does not. In addition, the expiration date on the insulin packaging is for unopened, refrigerated vials, disposable pens, or pen cartridges. Once opened, most vials of insulin last for 28 days, but many pens and pen cartridges are good for only 7, 10, or 14 days. Pump users should change their infusion set and the insulin in the pump reservoir every two to three days. These limits should be noted in the insulin package insert. If you’re not sure how long your opened container of insulin will last, ask a member of your diabetes care team or your pharmacist or call the manufacturer’s customer service number.
– Is your technique for taking your medicine adequate? If you take pills, be sure you’re taking them at the right time of day. Some pills must be taken right before meals to work effectively; others do not. If you take insulin by pen or syringe, review your injection technique with your diabetes care team. You should be aware that if you switch to a different syringe or insulin pen or from one to the other, the injection technique may differ.
– Are you storing your medicine properly? Insulin, as well as oral medicines, can lose potency if exposed to heat, cold, or moisture. Your best bet is usually to store opened containers of medicines you are currently using at room temperature. Unopened pills can also be stored at room temperature. Insulin that has not been opened should be stored in the refrigerator. Be careful not to place insulin in the particularly cold areas of the refrigerator — typically the meat compartment and at the backs of the main shelves — where it may freeze.
– Is your insulin being delivered adequately? If you use an insulin syringe or insulin pen, do you always use the same size needle? Some people find that a change in the needle length can disrupt their control. If you use an insulin pump, review the set-up of your infusion set with your diabetes care team to assure accurate insulin delivery. If you order pump supplies by mail, double-check your order when it arrives to make sure you received the correct supplies. Using a different size catheter or a different tubing length than usual may change the amount of priming necessary. (All pump users should have alternative methods of insulin delivery on hand should their pump malfunction or stop delivering insulin for any reason.) In addition, check your injection or infusion rhymes sites periodically. If toughening or scarring of the skin is present, this may affect absorption of your insulin.
– If you use an insulin pump, is the battery power sufficient? Avoid going to sleep at night or becoming preoccupied with other things when your battery is low. Be attentive to low battery warning alarms, and change your batteries promptly when they sound. Don’t wait until you’ve used the last drop of energy in your battery.
– Are you taking any other medicines that could affect your blood glucose level? Certain types of drugs — including prescription drugs, over-the-counter drugs, and herbal preparations — may contribute to hyperglycemia. Common prescription drugs that have a tendency to increase blood glucose levels include corticosteroids (used to treat inflammation) and thiazide diuretics (used to treat high blood pressure).
Any time you receive a prescription for a new drug, whether for a diabetes-related condition or not, ask your doctor if it may have any effects on your blood glucose levels. In addition, tell your health-care team about any over-the-counter medicines or alternative therapies you use so that together you can determine whether those substances or practices are having an effect on your blood glucose control.
During periods of stress, the body releases so-called stress hormones, which cause a rise in blood glucose level. In the short term, this gives the body the extra energy it needs to cope with the stress. But if a person doesn’t have adequate insulin circulating in his bloodstream to enable his cells to use the extra energy, the result will be hyperglycemia. And if stress becomes chronic, hyperglycemia can also become chronic. Stress hormones may be released during physical, mental, and emotional stresses.
Physical stress. Injury, illness, infection, and surgery are some examples of physical stresses that often cause hyperglycemia. In fact, hyperglycemia may be a clue that an otherwise symptomless infection is present. Resolving hyperglycemia caused by physical stress generally involves both treating the underlying cause and treating the hyperglycemia itself with changes to the usual diabetes treatment regimen.
Because everyone can expect to be ill at some point, people with diabetes are encouraged to work out a sick-day plan in advance with their diabetes care team. Your sick-day plan should have specifics on what to eat and drink when you’re sick, over-the-counter products that are safe to use, as well as details on taking your usual medicines and adding supplemental insulin if needed. It should also indicate when to call your health-care provider.
Mental and emotional stresses. Psychological stresses such as difficulties with relationships, job pressures, financial strain, and even concerns about self-worth can contribute to hyperglycemia. If these issues become overwhelming, decreased attention to the diabetes treatment plan may also contribute to hyperglycemia. Learning stress-reduction techniques may help over the long term, and your diabetes care team may be able to help you identify other resources that can help you deal with feelings of overwhelming stress.
Hormones other than stress hormones can affect blood glucose levels, as well. Premenopausal women may experience higher-than-usual blood glucose levels about a week prior to menstruation, when levels of progesterone, estrogen, and other hormones involved in ovulation are changing. In addition, some women find that they have a tendency to eat more during this phase of the menstrual cycle, which may further increase blood glucose levels. It can be useful to track your menstrual cycle along with your blood glucose levels to determine whether your cycle is affecting your blood glucose levels and to learn to make adjustments to your diabetes regimen when needed.
During perimenopause, which can last for several years before the complete cessation of menstruation, the menstrual cycle becomes less and less consistent. This can upset the balance of blood glucose control due to the unpredictability of hormonal levels.
Pregnancy hormones also affect blood glucose control. In fact, insulin adjustments are often necessary every 7–10 days during pregnancy, especially during the second and third trimesters, to adjust for changes in hormone levels as well as for the weight increases that come with pregnancy. Because hyperglycemia can contribute to a number of complications during pregnancy, close monitoring of blood glucose control is essential during and ideally before pregnancy.
In men with diabetes, low testosterone levels may contribute to increased insulin resistance, which can contribute to hyperglycemia. However, while testosterone replacement therapy has become a topic of great interest among both consumers and medical professionals, few studies have examined the long-term effects of testosterone replacement. Men concerned about low testosterone should seek individual guidance from their doctors.
Some people with diabetes allow their blood glucose levels to run higher than recommended because they are afraid of developing hypoglycemia (low blood glucose). This fear is certainly normal, since hypoglycemia can cause a person to lose bodily control, but a better response to this fear is to learn to prevent episodes of hypoglycemia while keeping your blood glucose levels in the best possible control. If fear is causing you to let your blood glucose level run high, talk with your diabetes care team to work out a plan that will help you avoid both lows and highs.
Another potential cause of hyperglycemia is the intentional or deliberate omission of insulin doses. This behavior is often linked to the presence of an eating disorder. Omitting needed insulin allows blood glucose levels to run high enough to cause the body to eliminate glucose through the urine and therefore decrease calorie absorption. This practice can enable a person to control his weight and, over time, to lose weight, which may be the desired result. However, repeated omission of insulin can lead to diabetes complications, worsen existing complications, and even lead to coma and death. If you or someone you know is intentionally omitting insulin doses as a means of weight control, it is urgent that you seek help from your diabetes care team or a qualified mental health professional. Eating disorders can be treated; left untreated, they can cause devastating health consequences.
Managing hyperglycemia is important both to avoid long-term complications and to avoid the acute hyperglycemic states known as ketoacidosis and hyperosmolar hyperglycemia. These disorders can occur in people with Type 1 diabetes as well as those with Type 2 diabetes, although the risk of ketoacidosis is higher among people with Type 1 and the risk of hyperosmolar hyperglycemia is higher among elderly people with Type 2.
Ketoacidosis is characterized by high blood glucose levels (over 250 mg/dl), the presence of ketones in the blood or urine, and dehydration. In hyperosmolar hyperglycemia, blood glucose levels are typically extremely high (over 600 mg/dl), and small amounts of ketones may be detectable in blood or urine. Emergency care in the hospital may be needed to reverse ketoacidosis or hyperosmolar hyperglycemia.
Infection, which, as noted earlier, causes the release of stress hormones, is the most common precipitating factor in the development of both problems. An interruption in insulin delivery from a pump or taking inadequate amounts of insulin by pen or syringe is also a common underlying factor in the development of ketoacidosis. Other factors that may lead to acute hyperglycemia are stroke, alcohol abuse, pancreatitis, heart attack, trauma, and certain drug therapies.
Preventing episodes of severe hyperglycemia involves knowing the causes and symptoms of hyperglycemia, monitoring blood glucose levels often enough to catch hyperglycemia in its early stages, and having a plan to deal with hyperglycemia should it occur. The fact that infection is what commonly leads to ketoacidosis and hyperosmolar hyperglycemia underscores the importance of discussing sick-day management with your diabetes care team before you become sick.
Staying in check
The only way you can truly know your blood glucose level is to check it with your meter. You should discuss when and how often to monitor with your diabetes care team. A diabetes educator can help you determine the type of equipment that is best for you, as well as make sure you are familiar with how the equipment works. More important, with your doctor’s help, your diabetes educator can help you learn to self-manage your diabetes by working through the challenges of managing hyperglycemia.
Keep in mind that even with your best efforts in managing your diabetes, you may still experience high blood glucose from time to time. But if your blood glucose levels remain higher than your treatment goals on a regular basis despite your attempts to follow your diabetes treatment plan, talk to your physician. You may need to update your plan to meet your diabetes control needs.