Problems and pitfalls of sulphonylurea therapy in older patients

Careful use to minimize adverse events of oral antidiabetic medications in the elderly

INTRODUCTION

An increasing number of older patients has type 2 diabetes treated with different oral antidiabetic agents whose safety may raise concern considering some particularities of a heterogeneous elderly population.

AREAS COVERED

This article discusses some characteristics of older patients that could increase the risk of adverse events, with a focus on hypoglycemia. It describes the most frequent and/or severe complications reported in the elderly in both randomized controlled trials and observational studies with metformin, sulfonylureas, meglitinides, alpha-glucosidase inhibitors, thiazolidinediones, dipeptidyl peptidase-4 inhibitors (gliptins) and sodium-glucose cotransporter type 2 inhibitors (gliflozins).

EXPERT OPINION

Old patients may present comorbidities (renal impairment, vascular disease, heart failure, risk of dehydration, osteoporosis, cognitive dysfunction) that could increase the risk of severe adverse events. Sulfonylureas (and meglitinides) induce hypoglycemia, which may be associated with falls/fractures and cardiovascular events. Medications lacking hypoglycemia should be preferred. Gliptins appear to have the best tolerance/safety profile whereas gliflozins exert a cardiorenal protection. However, data are lacking in very old or frailty old patients so that caution and appropriate supervision of such patients are required. Taking advantage of a large choice of pharmacotherapies, personalized treatment is recommended based upon both drug safety profiles and old patient individual characteristics.

Future perspectives for insulinotropic agents in the treatment of type 2 diabetes-DPP-4 inhibitors and sulphonylureas

The introduction of dipeptidyl-peptidase IV inhibitors (DPP-4 inhibitors) brought a novel class of insulinotropic agents into the treatment options for type 2 diabetes. This paper compares the actions, clinical efficacy and safety of sulphonylureas with those of the DPP-4 inhibitors. First, the mode of action of both classes of antidiabetic agents is described. Then clinical studies for both substances in monotherapy and combination therapies are compared concerning their effects on glycaemic parameters and long-term duration of action. Hypoglycaemia incidence and other adverse effects are compared and data on cardiovascular parameters and endpoints are summarized. The effects of sulphonylureas and DPP-4 inhibitors on beta-cell function and beta-cell mass are highlighted. The present and future indications for both sulphonylureas and DPP-4 inhibitors are discussed.

Use of antidiabetic drugs in elderly patients

The objective of this review of the literature is to analyze the results of studies including diabetic patients aged 70 years and older. Although the risk of treatment is greater in this population because of co-morbid conditions and altered renal function, information on the pharmacokinetics and pharmacodynamics of antidiabetic drugs remains limited. Long-term experience with sulfonylureas is sufficient to establish certain general rules of use; but for biguanides and alpha-glucosidase inhibitors, problems of tolerance limit use; further data are needed on glinides and glitazones. Use of insulin or insulin analogs is frequent and prescription should be adapted to achieve an acceptable balance between the risk of hypoglycaemia and therapeutic goals.

A review of clinical experience with the prandial glucose regulator, repaglinide, in the treatment of type 2 diabetes

Repaglinide is a novel insulin secretagogue that was developed as a prandial glucose regulator for the treatment of people with Type 2 diabetes mellitus. It is used flexibly, taken prior to meals, in order to limit subsequent postprandial blood glucose excursions as well as the dependent basal blood glucose concentration. In theory, the pharmacological profile of repaglinide is well suited for this role. Taken at mealtimes, its relatively rapid-onset and short-duration of action counteract a fundamental pathophysiological aspect of this disease: attenuation of the prandial insulin response. The predominantly hepatic elimination profile and a lack of drug-drug interactions with repaglinide are also properties well suited for patients with Type 2 diabetes. Importantly, the pharmacokinetic properties of repaglinide, are expected to reduce the risk of hypoglycaemia in comparison to the conventional insulin secretagogues (sulphonylureas). A reduced risk of hypoglycaemia carries the advantage that patients are not obliged to consume meals at regular intervals supplemented by snacks, so caloric restriction is feasible and lifestyle not compromised. These theoretical advantages have now been largely borne-out by clinical studies and empirical experience. Placebo-controlled studies have consistently demonstrated the antidiabetic efficacy of repaglinide, with improvements having been shown in all indicators of glycaemic control. Double-blind, active-comparator studies have shown repaglinide to have an antidiabetic efficacy that is at least equivalent to sulphonylureas, even when food intake and dosing intervals were controlled according to the requirements of sulphonylureas. Pooled data from these studies have shown that the risk of severe hypoglycaemia is reduced by 60% (p = 0.03) when repaglinide is used in preference to sulphonylureas. There is also evidence that the blood glucose threshold at which symptoms of hypoglycaemia are perceived by patients may be better preserved during treatment with repaglinide than with sulphonylureas. Studies examining flexible prandial dosing with repaglinide have shown that good glycaemic control and a low risk of hypoglycaemia are achievable goals that are independent of the meal (and, hence, dosing) pattern chosen by the patient. Furthermore, when used in this way, repaglinide has not been associated with weight gain. In combination therapy, repaglinide has been shown to act in synergy with both metformin and troglitazone. The possibility of a 'new' basal-bolus regimen combining repaglinide and exogenous (neutral protamine hagedorn) NPH insulin strategy has also been investigated.

The use of sulphonylureas in the elderly

Type 2 diabetes mellitus is a heterogeneous disorder characterised by defects in insulin secretion as well as reduced insulin action. During aging, glucose intolerance will gradually develop, and this is manifested primarily by an increase in the postprandial blood glucose response while fasting blood glucose levels are often less elevated. Abnormal beta-cell secretion of insulin is a main feature of this. Treatment of elderly patients with type 2 diabetes mellitus focuses on reduction of (hyperglycaemic) complaints and prevention of the development or progression of secondary complications. Although regular physical activity and dietary measures, aiming at bodyweight normalisation, are the cornerstones of therapy, pharmacological treatment with oral blood glucose lowering-agents often proves necessary to control the hyperglycaemia. In the United Kingdom Prospective Diabetes Study (UKPDS) it was clearly shown that patients with type 2 diabetes mellitus who were intensively treated with oral blood glucose-lowering agents or insulin developed less microvascular complications. The question whether achievement of strict metabolic control is also of benefit in elderly patients, is still unanswered. Sulphonylureas are drugs which stimulate insulin secretion by enhancing the release of insulin from the pancreatic beta-cells without an effect on insulin synthesis. They are frequently used in the treatment of type 2 diabetes mellitus, and several preparations are available. In general, there are no major differences in effectiveness between the various sulphonylureas. Long term treatment with sulphonylureas will decrease fasting and postprandial plasma glucose levels by 3 to 5 mmol/L, and glycosylated haemoglobin by 20%. However, after its initial decline, plasma glucose level will often go up slightly during the following months to years. Sulphonylureas are usually well tolerated. Hypoglycaemia is the most frequently occurring adverse effect, which may be very serious and damaging in the elderly. It has been associated primarily with long-acting sulphonylureas, like chlorpropamide and glibenclamide (glyburide). Hypoglycaemic episodes may trigger serious events like myocardial infarction or stroke. Therefore, shorter-acting compounds like tolbutamide and gliclazide have been relatively well tolerated and appear to be the best choice to treat elderly patients. It is advisable to start with a low dose and increase the dose, when needed, in small steps. The efficacy of sulphonylureas is much greater when they are taken before a meal. Because of the fact that type 2 diabetes mellitus is a progressive disease, and residual beta-cell function decreases with time, insulin therapy may ultimately be warranted in a significant number of patients.

Sulfonylureas

Sulfonylureas have been available for the treatment of non-insulin-dependent diabetes mellitus (NIDDM) since the 1950s. With the introduction of new oral agents, there is a tendency to discount the value of sulfonylurea therapy. Sulfonylureas have the advantage of multiple formulations, low costs, minimal side effects, and demonstrated efficacy in controlling hyperglycemia. The major disadvantage of sulfonylureas is secondary failure, which may occur with all oral agents as part of the progression of NIDDM. Sulfonylureas should continue to play an important role in the treatment of NIDDM.

Diabetes mellitus in older patients. Is tight blood glucose control warranted?

Diabetes mellitus is a major health problem in the older population, where it is mainly of the non-insulin-dependent type [i.e. non-insulin-dependent diabetes mellitus (NIDDM)]. Epidemiological evidence and extrapolation of trial data from patients with insulin-dependent diabetes mellitus (IDDM) suggests that improving glycaemic control reduces the risk of developing microvascular complications (i.e. retinopathy, nephropathy and neuropathy) and also slows the rate of progression of these complications in patients with early disease. Macrovascular morbidity and mortality is, however, more common than microvascular disease in the older population and the evidence that improved glycaemic control significantly reduces the impact of macrovascular disease is weak. Thus, the overall benefits of tight glycaemic control are less well defined in older patients, who tend to have NIDDM, than in younger patients with IDDM. There are small but significant risks associated with tight glycaemic control in the older patient, including potentially fatal hypoglycaemia with sulphonyl-ureas and/or insulin, and fatal metformin-induced lactic acidosis. Patients at especially high risk of these complications can, however, be identified and inappropriate pharmacological intervention can be avoided.