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Am Fam Physician. 1999;60(7):1985-1992

A more recent article on management of type 1 diabetes is available.

See editorial on page 1914.

See related patient information handout on type I diabetes, written by the author of this article.

Tight glucose control with intensive therapy in patients with type 1 diabetes (formerly known as juvenile-onset or insulin-dependent diabetes) can delay the onset and slow the progression of retinopathy, nephropathy and neuropathy. Optimal blood glucose control is defined by a target glycosylated hemoglobin level of less than 7 percent, a preprandial glucose level of 80 to 120 mg per dL (4.4 to 6.7 mmol per L) and a bedtime glucose level of 100 to 140 mg per dL (5.6 to 7.8 mmol per L). This article provides guidelines to help family physicians teach patients with type 1 diabetes how to achieve tight glucose control to help minimize complications. Guidelines include maintaining blood glucose levels at near normal by taking doses of short-acting insulin throughout the day supplemented by a nighttime dose of intermediate-acting insulin, monitoring blood glucose levels frequently, following a prudent diet, exercising regularly and effectively managing hypoglycemia, as well as empowering patients to lead their control efforts and rigorously controlling other risk factors for cardiovascular disease. Support from physicians, family members and friends is crucial to the success of a regimen of tight glucose control.

Patients with type 1 diabetes (formerly known as juvenile-onset or insulin-dependent diabetes) have an increased risk of developing retinopathy, nephropathy, neuropathy, coronary heart disease, stroke and peripheral vascular disease. Complications like retinopathy eventually occur in virtually 100 percent of patients on conventional therapy.1 Clinical trials have provided a strong scientific basis in support of the potential benefits of tight glucose control.13

The Diabetes Control and Complications Trial (DCCT)3 represents the largest of these trials. The DCCT compared the effects of intensive therapy with those of conventional therapy. Intensive therapy consisted of three or more daily doses of regular insulin administered by injection or insulin pump; conventional therapy consisted of one or two daily injections of regular and intermediate-acting insulins. The primary prevention cohort initially had no evidence of retinopathy or nephropathy. Patients randomized to receive intensive therapy experienced a reduction of up to 75 percent in microvascular complications.3 A secondary prevention cohort4 included those with mild to moderate non-proliferative retinopathy with microalbuminuria. Those randomized to undergo intensive therapy experienced reductions exceeding 50 percent in microvascular complications. The intensive therapy group also experienced approximately 50 percent fewer cardiovascular events.4

Most patients with type 1 diabetes would benefit from tight control,1,3,5 but many physicians are not implementing such regimens. In one large study,6 40 percent of insulin-dependent diabetic patients had not undergone a single glycosylated hemoglobin (HbA1c) test in the past year; among those tested, mean HbA1c levels ranged from 8.5 to 9.1 percent (indicating suboptimal control).

Initiating and maintaining tight control is not easy. Without appropriate knowledge, physicians are not ideally positioned to guide patients through the challenges of tight control. This reduces the likelihood that physicians will advocate tight control and decreases the chance that their patients will adopt it.

This article provides family physicians with the information they should provide their patients so that tight control may be successfully attained and the risks of developing diabetic complications can be minimized.

Educational Guidelines for Patients with Type 1 Diabetes

A summary of educational guidelines for helping patients achieve tighter control of blood glucose levels is presented in Table 1. These guidelines are based on the author's experience as an internist, a specialist in preventive medicine and a patient who has practiced tight glucose control for more than 40 years.

Keep blood glucose levels within the normal range as much as possible.
Test blood glucose levels regularly, especially before bedtime.
Use regular insulin (Humulin-R) or insulin lispro (Humalog) before each meal.
Carry a syringe loaded with regular or insulin lispro.
Use a small dose of insulin zinc suspension (Lente) or isophane insulin suspension (NPH) at bedtime.
Know the onset, peak and duration of effect of the insulins you use.
Eat a prudent diet.
Exercise regularly.
Limit alcohol consumption to moderate amounts.
Learn the signs, symptoms and management of hypoglycemia.
Always carry a source of sugar.
Teach family, friends and coworkers about hypoglycemia.
Keep glucagon at home.
Call 911 only in an emergency.
Wear a medical alert bracelet or necklace.
Recognize and manage the effects of stress on blood glucose levels.
Notice how normal blood sugar levels improve your sense of well-being.
Become empowered and take control.
Lead a “normal” life.
Work to prevent the complications of diabetes.

1. Keep blood glucose levels within the normal range as much as possible.

It is important to provide patients with goals for blood glucose levels. The goals for blood glucose levels and HbA1c that were established by the American Diabetes Association (ADA) are similar to those used by the DCCT for intensive treatment (Table 2).3 To consistently achieve these goals, patients must appropriately balance caloric intake, physical activity and insulin dosage throughout each day. Patient knowledge of each of these components is crucial for attaining this balance.

Biochemical parameterGoal
Preprandial glucose measurement80 to 120 mg per dL (4.4 to 6.7 mmol per L)
Bedtime glucose measurement100 to 140 mg per dL (5.6 to 7.8 mmol per L)
HbA1c measurement< 7%

2. Test blood gluose levels regularly, especially before bedtime.

It is important for patients to monitor blood glucose levels several times daily and whenever they are uncertain about their levels. In the DCCT, patients in the intensive treatment arm tested their blood glucose levels three to four times each day, although this frequency may be reduced slightly once patients become proficient in tight control.

Bedtime levels are particularly important because hypoglycemia is more hazardous at night when symptoms may be unrecognized, potentially resulting in a convulsion or coma. If glucose levels are borderline or low before bedtime, patients should eat an appropriately-sized snack.

3. Use regular or insulin lispro before each meal.

Type 1 diabetes can be tightly controlled only with regular insulin taken multiple times throughout the day. Because of the slow onset and long duration of action associated with intermediate- and long-acting insulins, as well as the lack of relationship of peak action to mealtimes, their disadvantages outweigh their advantages for tight daytime control in most patients.

Regular or insulin lispro (Humalog) should be administered before each meal, with the dosage based on the number of calories to be consumed. Approximately 10 units of insulin are required per 500 calories. Additional insulin may be needed if the patient's blood glucose level rises above recommended levels. Patients using insulin lispro may require a small amount of intermediate-acting insulin in addition to maintain blood glucose levels during gaps in coverage. Some patients may prefer using an insulin pump to deliver insulin. The main disadvantage of these devices is their cost.

4. Carry a syringe loaded with regular insulin or insulin lispro.

Patients should always carry insulin with them so it is available when needed. This allows them to be flexible about mealtimes and to accommodate an occasional snack. Plastic syringes can be used multiple times without danger of infection, provided the needle is recapped after each use.7 They can be reused safely until either the needle dulls or the dose levels become illegible, thereby saving considerable expense. Alternatively, patients can use pens with insulin cartridges, although they are somewhat expensive.

5. Take a small dose of intermediate-acting insulin zinc suspension or isophane insulin suspension at night.

If patients do not use an insulin pump and their bedtime blood glucose levels are within the normal range, they should take a small dose of insulin with intermediate duration (e.g., 4 to 8 units of insulin zinc suspension [Lente] or isophane insulin suspension [NPH]); otherwise, their blood glucose level will gradually rise during the night.8 If bedtime levels are high, a little regular insulin should be added to avoid frequent nocturia.

6. Know the onset, peak and duration of insulins used.

It is important to teach patients how quickly various types of insulin take effect, when they peak and how long their effects persist. The characteristics of the most commonly used insulins are shown in Table 3. Each type of insulin has distinct advantages and disadvantages. For example, the rapid action of insulin lispro carries one advantage over regular insulin, slightly better control of the postprandial rise in blood glucose, and two disadvantages, a much more rapid onset of hypoglycemia, with less time for premonitory symptom recognition, as well as a shorter duration of action. The intermediate-acting insulins have the advantage of longer duration, but the disadvantage of slower onset and potential problems if a meal is delayed.

Type of insulinOnsetPeakDuration
Insulin lispro (Humalog)5 minutes1 to 2 hours3 to 4 hours
Regular insulin15 minutes3 to 4 hours6 to 8 hours
Insulin zinc suspension (Lente) and isophane insulin suspension (NPH)1 hour6 to 8 hours12 hours
Extended insulin zinc suspension (Ultralente)1 hourNone24 hours

7. Eat a prudent diet.

A high blood cholesterol level increases the risk of developing coronary heart disease, stroke, peripheral vascular disease and hypertension.9 It may also increase the risk of developing retinopathy.10 Thus, patients should follow a prudent diet to help keep their cholesterol level low.11 Patients with diabetes should limit dietary fat to 30 percent or less of calories, with less than 10 percent from saturated fat. Diets should emphasize whole-grain products (six to 11 servings per day), fruits (two to four servings per day) and vegetables (three to five servings per day), meat, fish and poultry (two to three servings per day), dairy products (two to three servings per day) while fats and oils should be eaten sparingly. Diabetic patients can consume occasional sweets but may require additional regular insulin to keep their blood glucose levels normal.12 To reduce the risk of developing hypertension, sodium intake should be less than 2,400 mg per day, and normal weight should be maintained.13

8. Exercise regularly.

Regular physical activity is even more important for diabetic patients than for those without diabetes.14 Yet only about one third of patients with diabetes exercise regularly.15 Exercise improves blood glucose and high-density lipoprotein (HDL) cholesterol levels, reduces the risk of developing coronary heart disease, decreases stress and makes patients feel better.16 It also helps prevent weight gain, a potential consequence of tight control.3

Patients should strive to exercise on most, if not all, days.16 To accommodate the effects of exercise on blood glucose levels, patients must either reduce their insulin dosage or consume extra calories before exercise. They should be aware that insulin is absorbed and peaks more rapidly during exercise, especially when the medication is injected into the leg.

9. Limit alcohol consumption to moderate amounts.

Alcohol can blunt the release of glucose by the liver, thereby exacerbating hypoglycemia. Alcohol may also decrease patient recognition of hypoglycemia. Diabetic patients must be careful to maintain normal blood glucose levels when drinking. Patients should limit alcohol consumption to one to two drinks daily.

10. Learn the signs, symptoms and management of hypoglycemia.

Hypoglycemia manifests itself in many ways. Symptoms may include fatigue, slowness in speech or movement, confusion, irrationality, irritability, weakness, unexplained diaphoresis, pallor, twitching, headache or hunger. The symptom may be as subtle as a yawn or as dramatic as a feeling of imminent collapse. Symptoms may vary on different occasions. Hypoglycemia may be treated with juice, soda or another food containing sugar; overtreatment should be avoided because it can initiate a cycle of hyperglycemia followed by hypoglycemia.

Physicians should counsel patients not to feel embarrassed or stigmatized by hypoglycemia. Physicians and nonphysicians tend to assume that if diabetic patients become hypoglycemic, they must have done something wrong. The DCCT found that the tighter the patient's control was, the more frequently hypoglycemia occurred, despite taking the best precautions.3 Patients should analyze each episode to learn whether they could do something to reduce the chances of recurrence.

11. Always carry a source of sugar.

Hypoglycemia generally leads to a somewhat urgent need to rapidly increase the patient's blood glucose level. Because food is not always readily available, it is important for patients to always carry some source of sugar in case they become hypoglycemic. A vial of sugar or hard candy is particularly useful and easy to carry.

12. Teach loved ones, friends and coworkers about hypoglycemia.

Most of the time, diabetic patients can recognize and manage episodes of hypoglycemia, and occasionally they cannot. Either the patients or their family physicians should teach persons who will be in frequent contact with them about the signs and treatment of hypoglycemia, the occasional need to overcome denial associated with the confusion induced by hypoglycemia, and the importance of remaining calm during an episode. Their support and understanding of tight control is crucial. If the patient requires assistance, they need simply provide a source of sugar, such as soda, juice, ice cream, a candy bar or jam. Patients normally recover rapidly; if not, additional sugar can be given.

13. Keep a supply of glucagon at home.

Occasionally, patients lapse into a coma that is associated with extreme hypoglycemia. The two primary means for a non-physician to handle this condition are to provide a source of sugar such as juice, if the person can swallow, or to give a single injection of glucagon. Either way, the patient will awaken quickly.

14. Call 911 only in a true emergency.

Hypoglycemia does not normally require transport to a hospital. Such action may delay appropriate treatment as noted in guidelines 11 through 13, thereby harming the patient. Management in an emergency department is normally unnecessary unless these steps fail. However, emergency department personnel can provide helpful information by telephone if needed.

15. Wear a medical alert bracelet or necklace.

A medical alert bracelet or necklace identifying the patient as a diabetic is important. It can assist strangers, including health care personnel, in recognizing that unusual behavior or coma is a result of hypoglycemia. It also reflects patient recognition and acceptance of being diabetic.

16. Recognize and manage the effects of stress on blood glucose.

Stress can play havoc with blood glucose control. Blood glucose levels rise in some patients under the stress of infection, calling for additional insulin. Further, hypoglycemia may go unrecognized because of patient inattention related to stress. Stresses that may be associated with an increased risk of unrecognized hypoglycemia include problems at work, difficulties in personal relationships and traveling across multiple time zones. Patients should be particularly vigilant about hypoglycemia while under stress.

17. Notice how normal blood glucose levels improve your sense of well-being.

A powerful motivator for practicing tight glucose control each day is that patients feel much better when their blood glucose level is normal. They have more energy and avoid the “washed-out” feeling caused by hyperglycemia. It is useful to teach patients about this phenomenon. Otherwise, they may fail to recognize the correlation between their blood glucose level and the way they feel. Understanding this correlation provides daily positive reinforcement for tight control.

18. Become empowered and take control.

Tight glucose control requires day-to-day regulation. Only the patient can successfully accomplish this regulation. For this process to be successful, family physicians must empower their patients to take the lead in controlling the disease. Patients should be taught to adjust insulin dosages, food intake and exercise levels without waiting for physician approval. Encouraging active involvement in daily treatment decisions gives patients the responsibility for determining the quality and length of their lives.

Patient empowerment can be a powerful tool. In a recent clinical trial, patients with either type 1 or type 2 (formerly known as non–insulin-dependent) diabetes were randomized to participate in either an immediate or a delayed patient education and empowerment program.17 Ninety-five percent of those who were randomized to the immediate program reported making changes in diet, exercise and/or frequency of glucose monitoring. Patients in the immediate-program group showed significantly greater improvements in self-efficacy and HbA1c levels than those in the delayed-program group.

19. Lead a normal life.

Diabetes is classified as a handicap under the Americans with Disabilities Act. However, whether one feels handicapped depends largely on one's state of mind. Patients with diabetes can do virtually anything persons without diabetes can do. They just need to be a little more careful. Family physicians can play a large role in determining whether their patients view themselves as “normal” or “handicapped.”

20. Do everything possible to prevent the complications of diabetes.

Clinical trials have clearly shown that the complications of diabetes are largely preventable. The most important factor in preventing complications is maintenance of tight glucose control. The tighter the control, the lower the incidence of microvascular complications. For each 10 percent reduction in HbA1c levels, the DCCT found a reduction of about 45 percent in the incidence of retinopathy.18 Similar reductions in the incidence of nephropathy and neuropathy occurred as HbA1c levels decreased.19

Diabetic patients can greatly reduce their risk of macrovascular complications by controlling other major risk factors for coronary heart disease and stroke, i.e., hypertension, high cholesterol levels and smoking. Clinical trials clearly show that controlling these risk factors reduces coronary heart disease and stroke incidence in patients with type 1 and type 2 diabetes.2022

Each risk factor is present in about 25 percent of adult diabetic patients.2325 Family physicians should screen for these risk factors and assist their patients in modifying them. To minimize risk, even more rigorous control of two risk factors may be warranted, i.e., maintaining low-density lipoprotein (LDL) cholesterol at less than 100 mg per dL (2.6 mmol per L)11 and blood pressure at less than 130/85 mm Hg.26 Taking one aspirin daily (325 mg) reduces the risk of developing coronary heart disease by 20 to 25 percent.27,28

Secondary prevention is also important to reduce adverse sequelae and progression of microvascular complications that may develop. Diabetic retinopathy can be successfully treated,29 and further progression can be reduced through tight control.3 Although the ADA recommends that patients undergo screening examinations by their primary care physician and an ophthalmologist at least annually,12 most primary care physicians may not be complying with this recommendation.30

Early nephropathy can be detected by screening for microalbuminuria. Progression can be reduced through control of hypertension,26 the use of angiotensin-converting enzyme (ACE) inhibitors31 and maintaining tight glucose control.3

Final Comment

The data confirming the value of tight glucose control in reducing long-term complications are strong. Translating the results from clinical trials into clinical practice represents an important challenge. Although initially such discussions will require an investment of time, the rewards in patient satisfaction, understanding and future health can be considerable. The ADA Web site at offers excellent patient education programs, newsletters and journals that can assist physicians in empowering their patients. Implementing and maintaining tight control can be stressful for patients, their families and friends. Physician support is critical, particularly in the early stages. All patients will not wish to undertake the challenges of tight control. However, they all deserve the opportunity to make that decision, after weighing the benefits and risks. For most, the brief distress from occasional hypoglycemia is more than offset by the benefits derived from preventing potentially devastating macrovascular and microvascular complications.

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