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Diabetes in the Elderly

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Article Index
Introduction
Carbohydrate metabolism
Diagnosis of DM
Clinical Presentation
Complications of DM 1
Complications of DM 2
Monitoring
Management part 1
Management part 2
Management part 3
Management part 4
Management part 5

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Sulfonylureas:

Approximately 70% of the prescriptions for these anti-diabetics are for individuals over the age of 60 years. The safety profile and easy dosage schedule make sulfonylureas the cornerstone of therapy in the treatment of type-2 DM in the elderly. Because type 1 DM is uncommon in older adults, most are eligible for a trial of oral agents when dietary management fails.

Hypoglycemia, however, is a major safety concern with sulfonylureas. Up to 20% of patients taking sulfonylureas experience symptoms of hypoglycemia over a six-month period. There are multiple factors associated with ageing that increase the risk of hypoglycemia, including the age related alteration of hepatic and renal functions that alter drug metabolism and excretion. Ageing is also associated with impairments in the autonomic nervous system and reductions in alpha- adrenergic receptor function suggesting decreased response to hypoglycemia in the elderly. This can be dangerous as they may not present with warning symptoms such as tremors, sweating or palpitation and may directly come with neuroglycopenic symptoms such as convulsions, focal neurological deficits or coma.

The elderly are frequent users of drugs that are known to increase the risk for hypoglycemia, including beta- blockers, salicylates, warfarin, sulfonamides, tricyclic anti-depressants and alcohol. Many elderly persons receive inadequate education regarding the signs and symptoms of hypoglycemia. Severe hypoglycemia may follow glibenclamide use in the elderly. Metabolism of this drug yields two active metabolites, and in the elderly, the clearance of these metabolites appears delayed. For this reason, glipizide and gliclazide, which have shorter half-lives and few or no active metabolites, are preferred sulfonylurea agents in the elderly diabetics.

One more concern with sulfonylurea therapy has been the ability of these agents to cause vasoconstriction of small vessels, including the coronary arteries. The latest generation sulfonylurea, glimepiride, appears to be more selective than the earlier agents. Besides exhibiting less hypoglycemia compared to glibenclamide, this drug appears to be more specific for islet cell potassium channels. Thus, in contrast to earlier sulfonylureas, glimepiride is less likely to produce coronary artery vasoconstriction. Sulfonylurea tablets should be taken half-hour before meals. The drug should be started at a low dose, about half of the standard, and gradually increased if required.

Biguanides:

In overweight and obese diabetics, with normal renal functions and stable cardio-respiratory status, biguanides can be used if diet alone is not sufficient or as an add-on therapy with sulfonylureas. When used alone, they do not produce hypoglycemia. Metformin should not be used in conditions that are associated with increased generation of lactate or its decreased clearance, such as renal insufficiency, hepatic disease, alcoholism, severe congestive cardiac failure, severe peripheral vascular disease, and severe chronic obstructive pulmonary disease. Metformin should be administered immediately after meals to avoid gastrointestinal disturbances. Starting with a smaller dose can reduce this adverse effect.

Alpha- Glucosidase inhibitors:

Acarbose is an alpha- glucosidase inhibitor and reduces post-prandial hyperglycemia with lesser effect on fasting glucose levels. The advantage of acarbose in the elderly is its safety profile. However, gastrointestinal disturbance is the major adverse effect of acarbose. Starting with a smaller dose and gradually increasing the dosage if required can minimize this.

Repaglinide:

Repaglinide is a short-acting insulinotropic antidiabetic agent. Acting principally by augmenting endogenous insulin secretion from the pancreas in response to a meal, this controls the postprandial glucose excursions. This is a short- acting drug and can be taken with meals. The safety and efficacy of repaglinide appear to be similar in geriatric and younger patients.

Thiazolidinediones:

There are currently three drugs in this group - troglitazone, rosiglitazone and pioglitazone - of which the former has been withdrawn due to fatal hepatotoxicity. At present, there is no evidence that the latter two drugs have a similar hepatotoxicity, but precaution should be taken in patients with liver dysfunction. These are used alone (monotherapy) or in combination with sulfonylureas, metformin, or insulin for the management of type 2 DM. They act principally by increasing insulin sensitivity in target tissues, as well as decreasing hepatic gluconeogenesis. These are insulin sensitizers that act without stimulating insulin release from pancreatic beta cells, thus avoiding the risk of hypoglycemia. Hence these may be well suited for use in the elderly. The clinical usage recommendations and pharmacokinetics of thiazolidinediones in the elderly are similar to those in the younger diabetics. However, cardiac function must be assessed in all patients before starting these drugs as they can precipitate cardiac failure in patients cardiac dysfunction. Liver enzymes should be monitored monthly for the first six months, every two months for the next 6 months, and every 3 to 6 months thereafter.

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