Educational Guidelines for Achieving Tight Control and Minimizing Complications of Type 1 Diabetes

American Family Physician,  Nov 1, 1999  by Stephen Havas

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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. (Am Fam Physician 1999;60:1985-98.)

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.1-3

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 nonproliferative 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.

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.

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.