Improved Glycemic Control Reduces Risk of Diabetes-Related Complications
Daniel Tessier, MD, MSc, FRCPC, CSPQ
Sherbrooke Geriatric University Institute
Associate Professor, Faculty of Medicine
University of Sherbrooke
Introduction
The most recent Health and Nutrition survey in the United States demonstrated that the prevalence of diabetes is approaching 20% in Caucasian patients over the age of 70, and in certain ethnic groups, may be as high as 50%.1 Currently, the over 65 age group represents about 13 % of the total population, a percentage which is expected, by the year 2020, to increase to approximately 21% of the population. The majority of elderly diabetic patients have type 2 diabetes mellitus (DM), characterized by a gradually increasing glycemia that results from a combination of a resistance, at the cellular level, to the action of insulin, and a gradual decline of insulin secretion by the pancreas. A few years of asymptomatic disease may have elapsed prior to the diagnosis of DM being made, especially in the case of elderly patients. The following article will provide a brief review of the acute complications related to DM in the elderly with a particular focus on the evolution of the disease, side effects of treatment, and the vascular problems and acute infections that are often associated with this health problem.
Hypoglycemia and Hyperglycemia
All clinicians agree that, as a minimum, blood glucose levels should be sufficiently controlled to prevent the symptoms of hyperglycemia (the three classical "P's": polyuria, polyphagia and polydipsia). Data from the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated that improving the control of glycemia in middle-aged patients with type 2 DM, reduces the risk of microvascular, and perhaps even macrovascular, complications related to diabetes.2 Similarly, other observational studies of elderly diabetic subjects showed that an improvement in glycemic control is associated with a reduced risk of diabetes-related micro and macrovascular complications, as well as improvements in cognitive function.3-5 These data have encouraged clinicians to attempt to optimize blood sugar levels in their older patients, rather than merely controlling the levels to just below those that result in polyuria .
The principal metabolic defect in lean elderly diabetic patients is a profound impairment in the glucose-induced secretion of insulin. Insulin injections, and oral medication such as sulfonylureas that stimulate insulin secretion, have been widely used for the treatment of DM in elderly patients whose diabetes is not being controlled with dietary therapy. Particularly in the elderly, sulfonylureas are associated with an increased risk of hypoglycemic reaction and a higher fatality index.6
In the elderly patient, a hypoglycemic reaction may be very non-specific, and may present mostly with neurologic symptoms. A list of acute symptoms associated with a hypoglycemic reaction includes confusion, alteration in the level of consciousness, slurred speech, falls and blurred vision. During a suspected hypoglycemic event, the clinician should rely on a high clinical suspicion and the availability of a glucometre to measure capillary glycemia. Elderly subjects should be referred to diabetic teaching units to learn how to use the glucometre and how to manage hypoglycemic events, autonomously. Chlorpropamide and glyburide are the sulfonylureas that are associated with the greatest risk of hypoglycemia in the elderly. In one small trial, it was suggested that gliclazide, when compared to glyburide, is associated with a lower risk of hypoglycemia in the older population suffering from DM.7 In general, the initial doses of these drugs should be one half of those prescribed for younger people, and the dose should be increased more slowly. It is important to note that the physician has to make a cost/benefit analysis between tight glycemic control, which decreases the long-term complications of DM, and the