Diabetic neuropathy in elderly patients. What can be done?

ABSTRACT

The prevalence of diabetes mellitus increases markedly with age. Furthermore, advancing age is a strong risk factor for diabetic neuropathy, independent of the duration of diabetes mellitus and glycaemic control. Several biological changes occurring during the aging process may account for the facilitating effect of age on diabetic neuropathy. These include an increase in the production of advanced glycosylation end-products (AGEs), a defect in the polyol pathway, nerve vascular alterations and impaired resistance to oxidative stress. The clinical diagnosis of diabetic neuropathy is often difficult in elderly patients. The relationship between symptoms and neuropathy and that between neuropathy and diabetes mellitus are more difficult to ascertain in elderly patients due to age-related changes in the peripheral and autonomic nervous system and associated diseases frequently encountered in this population. Diagnosis of diabetic neuropathy is based on nerve conduction studies, vibratory perception threshold determination and assessment of autonomic function. For most of these tests, reference values are markedly influenced by age and their interpretation should use carefully age-adjusted reference intervals. Identification of peripheral diabetic neuropathy indicates a high risk of foot complications, such as ulcers and gangrene, often resulting in amputation, whereas cardiovascular autonomic neuropathy is associated with an increased risk of postural hypotension and coronary events. All these risks increase markedly with aging. Therapeutic trials in elderly patients with diabetic neuropathy are lacking. Treatment of diabetic neuropathy consists of achievement of better glycaemic control and treatment of symptoms related to neuropathy. Specific treatments capable of preventing or curing neuropathy are under investigation. The interesting results obtained with aldose reductase inhibitors in animal studies contrast with disappointing results in patients with diabetes mellitus. Other metabolic approaches, like antioxidants and gamma-linolenic acid, seem promising. Clinical complications of diabetic neuropathy in the elderly are often severe. Early detection is required, since at the present time a preventive approach is the most effective way to avoid or postpone debilitating complications. More research is needed to make effective curative treatments of diabetic neuropathy available.