Type 2 diabetes is a growing problem among the elderly population of the United States. The underlying defect that causes type 2 diabetes is insulin resistance. Factors that lead to worsening insulin resistance include aging, gaining weight and being sedentary. Since the population is aging, it is not surprising that the elderly increasingly comprise a larger proportion of patients with newly diagnosed diabetes. In 1993, 43% of the approximately 7.8 million people diagnosed with diabetes were over 65 years of age (Kenny et al., 1995).

Diagnosis and treatment of the older population have unique challenges. Due to physiologic changes associated with aging, the elderly patient with diabetes may not present with classic symptoms. With age, there is an increased prevalence of functional disability and comorbid illness that contributes to the complexity of managing diabetes. Treatment of the older patient with diabetes must take into consideration not only the standard microvascular and macrovascular complications, but also conditions such as cognitive impairment, falls and impaired function.

Many age-related changes can alter the clinical presentation of diabetes and make its diagnosis problematic. Typical symptoms of hyperglycemia such as polyuria, polydipsia and polyphagia may be masked (Meneilly and Tessier, 2001). The renal threshold for glucose increases with advanced age, and glucosuria may not be seen (Meneilly, 2000). Polydipsia can be absent, and the initial presentation among elderly patients may be dehydration with altered thirst perception and delayed fluid supplementation. More often, changes such as dry eyes, dry mouth, confusion, incontinence or complications relating to diabetes are the presenting symptoms.

Hypoglycemia is a risk of diabetes treatment. Studies of healthy elderly patients have shown that glucose counterregulation involving glucagon, epinephrine and growth hormone responses to hypoglycemia are diminished. This may contribute to the reduction in autonomic warning symptoms (Meneilly et al., 1994). Symptoms might not appear until there is severe hypoglycemia at levels <50 mg/dL due to these counterregulation changes.

The current American Diabetes Association (ADA) criteria for diagnosis of diabetes apply to all populations and are: on two separate occasions, either a fasting plasma glucose level ≥126 mg/dL, a random plasma glucose ≥200 mg/dL with symptoms or a two-hour oral glucose tolerance test (OGTT) ≥200 mg/dL. Since the ADA recommends that anyone over 45 be screened, all older individuals should be screened annually for diabetes.

Recent literature from the Diabetes Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe (DECODE) trials, which included elderly subjects, revealed that an OGTT ∂200 mg/dL increases the risk of all-cause mortality, even in the presence of a normal fasting glucose (European Diabetes Epidemiology Group, 1999). Although measuring fasting plasma glucose levels increases the detection of diabetes in younger patients, it may actually miss 31% of cases in older patients (DECODE Study Group, 1999). The two-hour OGTT is most useful in diagnosing diabetes in the elderly.

All complications of diabetes, including microvascular and macrovascular, can occur in older patients with diabetes. Older patients often present with these complications at the time of diagnosis. Some less-recognized complications seen in these patients are listed in the Table.

Often, elderly patients have cognitive impairments, limitations in their activities of daily living, undiagnosed depression and difficult social issues that may contribute to the development of complications. Coexisting health problems, such as dementia or psychiatric illnesses, may require a simplified approach to diabetes care.

Diabetes is associated with lower levels of cognitive functioning and greater cognitive decline in the elderly (Gregg et al., 2000). Prospective trials have not shown consistent improvements in cognition with tight glucose control, although observational studies note improved cognitive functioning with lower hemoglobin A1c (HbA1c) levels (Tun et al., 1990). The mechanisms by which diabetes is associated with cognitive impairment remain unclear.

The risks of hypoglycemia are higher in patients who are cognitively impaired. These patients often have impaired awareness of the autonomic warning symptoms of hypoglycemia even when they have been educated about them. They may also have delayed psychomotor responses to intervene in the correction of hypoglycemia (Thomson et al., 1991). Therefore, each patient's risk for hypoglycemia should be considered, and each patient's therapy should be individualized accordingly.

Common diabetic microvascular complications include retinopathy, nephropathy and neuropathy. Since patients may have type 2 diabetes for several years before the diagnosis is made, microvascular complications are often already present.

The value of controlling blood glucose in order to minimize the microvascular disease in type 2 diabetes has been well-established for younger populations. Data regarding whether tight glucose control improves mortality or improves function among the frail or institutionalized elderly are lacking.

Diabetic retinopathy is a common cause of blindness among all patients with diabetes. As in the young, good diabetic control among older patients can retard the onset of retinopathy (Morisaki et al., 1994). Cataracts are more common and occur at an earlier age among individuals with diabetes. Thus, patients should be referred for annual thorough eye examinations.

Diabetic nephropathy is a common cause of renal failure in the geriatric population. Significant improvements in nephropathy can be made independent of blood glucose control. Angiotensin-converting enzyme (ACE) inhibitors and blood pressure control to <130/80 can reduce nephropathy.

Neuropathy deserves special attention because this complication increases in prevalence as patients with diabetes age. It is extremely common and occurs in 50% of patients with type 2 diabetes over 60 years of age (Young et al., 1993). Neuropathy leads to gait imbalances and is a risk factor for falls.

Cardiovascular, cerebrovascular and peripheral vascular disease are more common among all patients with diabetes and are a cause for excess mortality (Croxson et al., 1994). These long-term macrovascular complications cause considerable functional impairment in elderly patients (Sinclair, 1999).

The management of the elderly patient with type 2 diabetes has different goals and objectives than does that of the younger patient. The patient's life expectancy, coexisting medical or psychiatric disorders, and the patient's willingness and ability to comply with the proposed treatment are important considerations (Halter, 1998). Medical therapy can contribute to the development of complications in older patients. The following agents may require modifications when used in the elderly.

Biguanides (such as metformin [Glucophage]) do not cause hypoglycemia when used independently. However, they need to be used with caution in older patients because they can cause anorexia and weight loss (Lee and Morley, 1998).

Metformin can place patients at risk for lactic acidosis if they have renal insufficiency. Elderly patients have decreased muscle mass, and their serum creatinine may not reflect the true creatinine clearance. Therefore a 24-hour urine sample should be ordered for patients over 70.

First-generation sulfonylurea agents (e.g., chlorpropamide [Diabinese]) should be avoided in the elderly because of their long half-life and increased propensity for hypoglycemia in the elderly.

The thiazolidinediones (e.g., rosiglitazone [Avandia], pioglitazone [Actos]) are not indicated in elderly patients with evidence of heart failure or liver disease. In elderly patients who do not have those contraindications, these medications can be useful since they do not cause hypoglycemia as monotherapy.

The risk of severe hypoglycemia associated with insulin increases with age (Stepka et al., 1993). Initiation of insulin in elderly patients with type 2 diabetes should be done with the involvement of the multidisciplinary team. A complete geriatric assessment should be performed first to assure that patients can comply with their regimens and to identify potential complicating factors. If there are caregivers, provisions for adequate respite programs should be made and offered to avoid caregiver burnout.

Ideal geriatric care requires a multidisciplinary approach. Successful diabetes care in the aging population requires an understanding of the physiology of aging and recognition of the special issues facing the elderly. As with any patient with diabetes, overall goals should aim at reduction of complications. In older patients, therapy should be individualized and include a functional assessment. Goals of therapy should aim toward optimizing function and minimizing complications that may cause loss of independence or early institutionalization.

Dr. Chau is assistant professor of medicine at the University of Nevada School of Medicine and the U.S. Department of Veterans Affairs Sierra Healthcare Systems.

Dr. Shumaker is associate professor of medicine at the University of Nevada School of Medicine and chief of geriatrics and extended care at the VA Sierra Healthcare Systems.

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Complications of Type 2 Diabetes in the Elderly