Diabetes in the Elderly

摘要

With the ageing of populations even in developing countries and the epidemic of diabetes sweeping across India, elderly diabetics form a major fraction of patients in the physicians' daily practice. The clinical presentation of diabetes in this subgroup is somewhat different from the younger group of patients, and calls for emphasis on unusual features. Further, the diagnosis and management, including the choice of drugs are modified by the changed metabolism of the ageing patient. Lastly, the goals of therapy must be clearly defined keeping in mind the real danger of hypoglycemia in elderly diabetics. Introduction Advances in medical science and improved social conditions during the past few decades have increased the life expectancy of humans. This phenomenon of population ageing is universal. Almost 10% of the population in developed countries and 5 to 8% in the developing countries are over the age of 60 years. In India, the absolute size of the elderly population is considerable and the projected figure for the year 2001 is 70 million.1 The prevalence of diabetes mellitus (DM) increases with age. In India, 20% of the elderly population has DM.2 In addition, over 25% of older persons have impaired glucose tolerance (IGT).3 The majority of older individuals with diabetes have type 2DM. 4 In the Diabetic Clinic at our hospital, about 45% (n= 680) are over 60 years old, with a male to female ratio of 3:2. Carbohydrate Metabolism In The Elderly Most studies have revealed rises in glucose levels, especially post prandial blood glucose levels that directly correlate with age. Fasting blood glucose increases by 1 to 2 mg/dL per decade, with postprandial blood glucose levels increasing up to 15 mg/dL per decade.6 The relative importance and mechanisms of deficient insulin secretion and action during ageing are still debated. The increased hyperglycemia may be due to delayed suppression of hepatic glucose output owing to impaired insulin release, and reduced rate of peripheral uptake. The predominant problem of lean elderly diabetics is insulin deficiency. Obese patients have both insulin resistance and relative insulin deficiency. Major contribution also comes from extrinsic factors like diet, medication, activity, chronic illness and stress, which reduce the muscle mass and alter other organ functions resulting in glucose intolerance.6 Diagnosis Of Diabetes In The Elderly The current ADA guidelines for the diagnosis of DM, do not adjust glycemic criteria for age.7 This decision was based on the evidence that even mild hyperglycemia is associated with poor health outcomes as reported in younger individuals. Although IGT may be associated with an increased risk of cardiovascular disease, it does not predispose to chronic diabetic microvascular complications.As post-challenge glucose levels in particular rise with increasing age, GTT is not indicated for diagnosis. The best screening test for DM in older adults is determination of fasting plasma glucose levels.8 Routine urine sugar testing for screening diabetes mellitus is inaccurate and is not recommended. Further, benign prostatic hyperplasia and diabetic autonomic bladder dysfunction are commonly found in elderly males and it alters the glucose content of urine due to the residual urine present in the bladder. In such patients, if at all urine sugar testing has to be done, the ‘double-voiding technique' should be used. The patient should be asked to discard one sample and the next sample collected after half-hour should be used to assess urine sugar.Because a substantial number of elderly patients have undiagnosed diabetes, and these patients appear to have an increased incidence of macrovascular events, the current criteria recommend that a fasting glucose value be performed every 3 years in elderly patients at low risk for diabetes and yearly in patients at high risk, such as those with obesity, hypertension, family history, or the presence of complications commonly associated