University of Toronto - Faculty of Medicine

 

Author
The revision of this chapter was prepared by Henry Halapy, RPh

Although there is no universally agreed upon definition of the age at which a person is considered elderly, generally as people pass the ages of 60-65 years of age, there is a slow progression of frailty until the end of life. The incidence of type 2 diabetes increases with age as insulin secretion tends to decrease. This chapter focuses on aspects of management of diabetes which may be unique to the elder population.

 

• Lifestyle interventions, including moderate weight loss and regular physical activity should be considered a therapeutic approach to prevent type 2 diabetes in elderly patients at risk.
• Medications such as acarbose and rosiglitazone have been shown to be effective in the prevention of type 2 diabetes in elderly patients at risk. However, metformin does not seem to be effective in patients aged over 60 in preventing type 2 diabetes when compared to younger patients.

 

• The capacity to metabolize carbohydrate decreases with age. During oral glucose tolerance tests, blood glucose levels are higher in the healthy aged than in younger subjects but are still within the limits set for younger subjects.
• The diagnostic criteria for diabetes mellitus and impaired glucose tolerance are the same in the elderly as in younger people.

 

• The same targets for glycemia, blood pressure and lipids apply to otherwise healthy elderly as to younger people with diabetes; however, in the presence of multiple co-morbidities, high levels of functional dependency or limited life expectancy, goals should be less stringent in order to avoid significant hypoglycemia. Severe hyperglycemia should be avoided regardless of age.
• Elderly patients should be referred to a diabetes health care team as multidisciplinary intervention has been shown to improve glycemic control (decreased medication use, weight loss).
• Nutrition and physical activity remain the initial management strategies, supplemented by oral antihyperglycemic agents, combination therapy, and insulin if needed.
• The nutritional management of the elderly is essentially the same as that for younger individuals (see Chapter 3). Total calories should aim to achieve a desirable body weight. The diet should contain the appropriate distribution of fat (<30%), carbohydrate (50-60%), fibre (25-35g/day), protein (15-20%) and sodium and should be individualized to accommodate personal preferences, lifestyle, culture and readiness to change. Alcohol may be allowed in moderation (<14 drinks per week for men, <9 drinks per week for women, although elderly patients may only tolerate lower levels of alcohol), but patients should be advised of the risks of alcohol. In addition, social situations, coexisting medical conditions, and causes of involuntary weight loss need to be taken into consideration.
• Aerobic or resistance exercise is recommended for elderly patients in whom it is not contraindicated.
• Evidence of microvascular or macrovascular disease should be sought at the time of diagnosis.

 

• Management of diabetes in the elderly involves using the same guidelines as for younger individuals; however, special precautions are needed for administering oral agents in the elderly especially in the presence of renal, hepatic or cardiac disease.
• Metformin, alpha-glucosidase inhibitors, thiazolinediones, meglitinides, and sulfonylureas can all be used in elderly patients. For lean elderly patients with type 2 diabetes, agents that promote insulin secretion should be selected, while in obese elderly patients with type 2 agents, agents that lower insulin resistance should be selected.
• Alpha-glucosidase inhibitors are modestly effective for glycemic control, but tolerance of these agents is a problem.
• Thiazolinediones are effective but associated with an increased incidence of edema and CHF in the elderly. These agents should only be used with caution in elderly patients with cardiovascular disease.
• Sulfonylreas are effective agents in the elderly, but hypoglycemia remains the main adverse effect of concern. The incidence of hypoglycemia associated with the use of sulfonylureas increases exponentially with age and appears to be higher with glyburide, especially in the presence of renal dysfunction. Other risk factors for drug induced hypoglycemia include intercurrent illness, cardiac disorders and previous strokes, polypharmacy, frequent hospitalizations, low food intake, diarrhea, alcohol intake, and decreased hepatic drug metabolism. Further, counterregulatory responses to hypoglycemia may be attenuated with advanced age. Gliclazide (both regular and long-acting formulations) and glimepiride are preferred choices, as they are associated with a lower incidence of hypoglycemia compared to glyburide. One study has even shown that the long-acting formulation of gliclazide has lower rates of hypoglycemia compared to glimepiride. In addition, there is some retrospective evidence that suggests that older sulfonylureas may be associated with higher rates of myocardial infarctions.
• Meglitinides may reduce the risk of hypoglycemia compared to glyburide and would be preferred in elderly patients with irregular eating habits.
• Sitagliptin has been studied in the elderly; although it will help with reduction of postprandial hyperglycemia and is weight neutral, the long-term safety of this class of agents is unknown at present.
• Insulin therapy poses special concerns in some elderly patients. Dosage errors may result from issues with concentration and memory, failing eyesight and manual dexterity. Use of premixed insulins or prefilled insulin pens as an alternative to mixing insulins should be considered to reduce the risk of dosage error and is preferred by elderly patients. Multiple daily injections or CSII regimens may be considered in elderly patients with poor control. They may improve glycemic control with good safety and patient satisfaction.
• Elderly patients should be treated for hypertension and hyperlipidemia concomitantly as suggested (see macrovascular chapter). The same agents may be used in elderly patients as in younger patients.
• As elderly patients frequently are on multiple medications, it is important to consider potential drug interactions between diabetes agents and other medications. Drug interactions between sulfonylureas and agents that either inhibit (fluconazole, cimetidine, ciprofloxacin) or induce (rifampin) cytochrome P450 may cause hypoglycemia or hyperglycemia to occur respectively. Trimethoprim decreases renal excretion of sulfonylureas, leading to potential for hypoglycemia. Sulfonylureas in turn may potentiate the anticoagulant action of warfarin . Rosiglitazone and pioglitazone are predominantly metabolized through the cytochrome P450 system (cytochromes 2C8, and 2C8/3A4 predominantly) and can therefore also be affected by inhibitors and inducers of the P450 system. As repaglinide is metabolized by 3A4 and 2C8, blood levels of repaglinide may be increased by ketoconazole, erythromycin/ clarithromycin and trimethprim. Nateglinide is metoblized by 3A4 and 2C9 and may potentially have interactions with inhibitors and inducers of these isoenzymes. Sitagliptin is predominantly renally excreted and minimally metabolized; therefore, it is unlikely to have drug interactions involving cytochrome P450. It may, however, increase digoxin levels.

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