Diabetes Mellitus

All clinicians agree that blood glucose levels should be controlled sufficiently well to reduce the symptoms of hyperglycemia. There is less consensus regarding the optimal degree of blood sugar control in elderly diabetic patients. This is due in part to the fact that no randomized controlled trials involving elderly subjects have definitively assessed whether tight blood glucose control reduces the risk of disease and disability in this age group. The United Kingdom Prospective Diabetes Study (UKPDS) recruited middle-aged patients with type 2 diabetes and randomized them to either intensive blood glucose control with metformin, sulfonylurea, or insulin or a control group with conventional treatment. The UKPDS data did demonstrate that improved glycemic control reduces the risk of microvascular complications related to diabetes, and perhaps macrovascular complications in middle-aged patients. Furthermore, in observational studies of elderly subjects, improved glycemic control is associated with a reduced risk of microvascular and macrovascular complications related to diabetes (Kuusisto et al.; Morisaki et al.), as well as with improved cognitive function (Meneilly et al.). Based on these data, it is recommended that goals for control in elderly patients should be less than 7 millimol/liter before meals and less than 10 millimol/liter after meals.

Nonpharmacological intervention. Achieving optimal blood sugar control in elderly persons with diabetes is challenging. These patients take numerous medications, have multiple comorbidities, and often live in challenging social situations. Because of the complex nature of these patients and the need for lifestyle modifications, a team approach is essential. A structured diabetes teaching program will improve blood sugar control, compliance with therapy, and quality of life in older patients. Self-monitoring of blood sugar level at home is possible with a portable device called a glucometer. The self-monitoring of blood sugar constitutes a key aspect of diabetic management. Levels of HbA1c (glycosilated hemoglobin) and/or fructosamine are the standard laboratory measures of long-term glycemic control in older individuals, and should be assessed at regular intervals (Meltzer et al.).

Exercise programs have been shown to improve the sense of well-being, glucose levels, and lipid levels in elderly patients with diabetes (Agurs-Collins et al.). Unfortunately, concomitant health problems often prevent elderly patients from participating in exercise programs, and optimal activity levels may be difficult to achieve. Thus exercise programs of even low and moderate intensity are of value in selected elderly patients.

Elderly patients with diabetes have diets that are too low in complex carbohydrates and too high in saturated fats, and they frequently do not comply with a diabetic diet. As noted above, multidisciplinary interventions have been shown to improve compliance with dietary therapy in aged diabetics. For community-dwelling elderly subjects, weight loss programs have been shown to result in substantial improvements in blood sugar control (Reaven et al.). In contrast, for frail elderly nursing home residents, diabetic diets complicate and increase the cost of care, and do not improve blood sugar control.

Pharmacological intervention. The principal metabolic defect in lean elderly patients with diabetes is profound impairment in glucose-induced insulin secretion. Medications that stimulate insulin secretion, such as sulfonylureas, have been widely used for the treatment of diabetes in elderly patients that is not controlled with dietary therapy. This kind of medication is associated with an increased risk of hypoglycemia, especially in the elderly. Chlorpropamide and glyburide are the sulfonylureas associated with the greatest risk of hypoglycemia in the elderly. Observational studies and small, randomized controlled trials suggest that glipizide and gliclazide are associated with a lower risk of hypoglycemia in the older population with diabetes (Brodows; Tessier et al.). In general, initial doses of these drugs should be half those for younger people, and should be increased more slowly. The role of newer insulin-stimulating drugs, such as repaglinide, remains to be determined for elderly patients with diabetes.

The UKPDS suggests that metformin, a member of the biguanide family, is an effective agent in obese middle-aged patients, and may be more beneficial than sulfonylureas in reducing the risk of morbid events. The main effect of metformin is to reduce insulin resistance. This drug results in substantial improvements in blood sugar control in obese elderly patients (Lalau et al.). Metformin should not be given to patients with creatinine values (blood indicator of kidney function) above 180 microns/liter, chronic liver disease, or significant congestive heart failure. Based on clinical experience, sulfonylureas and metformin can often be given in combination to elderly patients with diabetes to improve blood sugar control.

Because of their ability to improve insulin resistance, thiazolidinediones (pioglitazone and rosiglitazone) may also be a useful class of drugs for obese elderly patients. This class of drug improves insulin resistance. Pending the results of further studies in the elderly, this class of drugs should be reserved for the treatment of obese elderly patients whose blood sugar is not optimally controlled with another kind of antidiabetic medication. When thiazolidinediones are prescribed for the elderly, liver function should be monitored at regular intervals.

Alpha glucosidase inhibitors are a class of drugs that interfere with the action of the enzymes responsible for the digestion of complex carbohydrates and disaccharides at the brush border of the intestine. This class of drugs slows the absorption of glucose through the small intestine. Acarbose is the first of these drugs released for clinical use. A study has been published on the efficacy of this drug for elderly diabetes patients (Meneilly et al.). At present, acarbose should be considered as first-line therapy for lean elderly patients with a modest increase in fasting glucose levels.

Insulin therapy substantially improves blood sugar control with no adverse effect on the quality of life in patients who are inadequately controlled by oral agents (Tovi and Engfeldt). Elderly patients can make substantial errors when trying to mix different kinds of insulin in the same syringe (e.g., the rapid-acting R or Toronto insulin with the intermediate-acting N or NPH insulin). For this reason, insulin preparations that do not require mixing are preferable for them. In type 2 diabetes, insulin therapy is usually started ". . .with one dose of intermediate acting insulin in addition to pills given at different times of the day such as metformin and glyburide." However, many patients who are started on one daily dose of insulin need a second injection in order to control blood sugar.