Nateglinide alone and in combination with metformin improves glycemic control by reducing mealtime glucose levels in type 2 diabetes

Health and economic impact of combining metformin with nateglinide to achieve glycemic control: Comparison of the lifetime costs of complications in the U.K

BACKGROUND: To reduce the likelihood of complications in persons with type 2 diabetes, it is critical to control hyperglycaemia. Monotherapy with metformin or insulin secretagogues may fail to sustain control after an initial reduction in glycemic levels. Thus, combining metformin with other agents is frequently necessary. These analyses model the potential long-term economic and health impact of using combination therapy to improve glycemic control. METHODS: An existing model that simulates the long-term course of type 2 diabetes in relation to glycosylated haemoglobin (HbA1c) and post-prandial glucose (PPG) was used to compare the combination of nateglinide with metformin to monotherapy with metformin. Complication rates were estimated for major diabetes-related complications (macrovascular and microvascular) based on existing epidemiologic studies and clinical trial data. Utilities and costs were estimated using data collected in the United Kingdom Prospective Diabetes Study (UKPDS). Survival, life years gained (LYG), quality-adjusted life years (QALY), complication rates and associated costs were estimated. Costs were discounted at 6% and benefits at 1.5% per year. RESULTS: Combination therapy was predicted to reduce complication rates and associated costs compared with metformin. Survival increased by 0.39 (0.32 discounted) and QALY by 0.46 years (0.37 discounted) implying costs of pound 6,772 per discounted LYG and pound 5,609 per discounted QALY. Sensitivity analyses showed the results to be consistent over broad ranges. CONCLUSION: Although drug treatment costs are increased by combination therapy, this cost is expected to be partially offset by a reduction in the costs of treating long-term diabetes complications.

Metformin hydrochloride in the treatment of type 2 diabetes mellitus: a clinical review with a focus on dual therapy

BACKGROUND

Type 2 diabetes mellitus typically involves abnormal beta-cell function that results in relative insulin deficiency, insulin resistance accompanied by decreased glucose transport into muscle and fat cells, and increased hepatic glucose output, all of which contribute to hyperglycemia.

OBJECTIVE

This review examines the pharmacology, pharmacokinetics, drug-interaction potential, adverse effects, and dosing guidelines for metformin hydrochloride, a biguanide agent for the treatment of type 2 diabetes. Clinical trial data are reviewed, including efficacy and tolerability information, with a focus on studies of dual metformin therapy (metformin plus another oral agent or insulin) published from 1998 to the present. Pharmacoeconomic considerations are also discussed.

METHODS

Primary research and review articles were identified through a search of MEDLINE (1966-May 2003) and International Pharmaceutical Abstracts (1970-May 2003) using the terms metformin and/or Glucophage. Web of Science (1995-May 2003) was used to search for additional abstracts. The package inserts for metformin and metformin combination products were consulted. All identified articles and abstracts were assessed for relevance, and all relevant information was included. Priority was given to the primary medical literature and clinical trial reports.

RESULTS

Metformin is the only currently available oral antidiabetic/hypoglycemic agent that acts predominantly by inhibiting hepatic glucose release. Because patients with type 2 diabetes often have excess hepatic glucose output, use of metformin is effective in lowering glycosylated hemoglobin (HbA1c) by 1 to 2 percentage points when used as monotherapy or in combination with other blood glucose-lowering agents or insulin. Other metabolic variables (eg, dyslipidemia, fibrinolysis) may be improved with the use of metformin. Body weight is often maintained or slightly reduced from baseline. Metformin is well tolerated and is associated with few clinically deleterious adverse events. The most important and potentially life-threatening adverse event associated with its use is lactic acidosis, which occurs very rarely.

CONCLUSIONS

Metformin has multiple benefits in patients with type 2 diabetes. It can effectively lower HbA1c values, positively affect lipid profiles, and improve vascular and hemodynamic indices. Adverse effects are generally tolerable and self-limiting. The availability of products combining metformin with a sulfonylurea or rosiglitazone has expanded the array of therapies for the management of type 2 diabetes.

Treating diabetes using oral agents

Since the development and release of sulfonylureas for the treatment of T2DM, additional oral glycemic control agents with different mechanisms of action have allowed for more flexibility in targeting drug to patient. Based on available evidence, metformin monotherapy is preferred for the vast majority of T2DM patients who are overweight or obese. Combination therapy has further improved glycemic control. However, limitations in use, including the challenges of side effects, to that of secondary oral agent failure will inevitably occur over time. These challenges leave ample room for the development of agents that address the pathophysiology not only of treating insulin resistance and decreasing insulin production but also of preventing or delaying the development of diabetes in populations at risk.

Metformin: new understandings, new uses

Metformin, a biguanide, has been available in the US for the treatment of type 2 diabetes mellitus for nearly 8 years. Over this period of time, it has become the most widely prescribed antihyperglycaemic agent. Its mechanism of action involves the suppression of endogenous glucose production, primarily by the liver. Whether the drug actually has an insulin sensitising effect in peripheral tissues, such as muscle and fat, remains somewhat controversial. Nonetheless, because insulin levels decline with metformin use, it has been termed an 'insulin sensitiser'. Metformin has also been shown to have several beneficial effects on cardiovascular risk factors and it is the only oral antihyperglycaemic agent thus far associated with decreased macrovascular outcomes in patients with diabetes. Cardiovascular disease, impaired glucose tolerance and the polycystic ovary syndrome are now recognised as complications of the insulin resistance syndrome, and there is growing interest in the management of this extraordinarily common metabolic disorder. While diet and exercise remain the cornerstone of therapy for insulin resistance, pharmacological intervention is becoming an increasingly viable option. We review the role of metformin in the treatment of patients with type 2 diabetes and describe the additional benefits it provides over and above its effect on glucose levels alone. We also discuss its potential role for a variety of insulin resistant and prediabetic states, including impaired glucose tolerance, obesity, polycystic ovary syndrome and the metabolic abnormalities associated with HIV disease.

A Comparison of Agents Used to Manage Type 2 Diabetes Mellitus

In patients with type 2 diabetes mellitus, the traditional method of initiating therapy with a sulfonylurea and increasing the dosage until maximum levels are reached before adding an insulin-sensitizing agent has persisted and should be re-evaluated. Similarly, the current practice of starting therapy with one agent and increasing to maximum dosage before adding a second agent, rather than starting with combination therapy, also needs to be addressed. There is much evidence to suggest that initiating therapy with lower doses of two agents that have complementary effects can increase the overall efficacy and decrease the incidence of adverse effects. Clearly, there is a need for a paradigm shift away from the traditional approach of therapy using insulin secretagogues to a more pathophysiologic approach using an insulin-sensitizing agent, such as the thiazolidinediones. The thiazolidinediones have been shown to reduce insulin resistance, improve the ability of beta-cells to produce insulin, and decrease cardiac risk factors. By reducing insulin resistance, improving glycemic control, and preserving beta-cell function with a thiazolidinedione early in the course of therapy, it is likely that durable glycemic control will be achieved and both microvascular and macrovascular complications may be reduced. Furthermore, early use of an insulin-sensitizing agent either alone or incombination is expected to improve both acute and long-term outcomes in patients with type 2 diabetes.

Tolerability Profile of Metformin/Glibenclamide Combination Tablets (Glucovance??)

It is important to manage blood glucose intensively in patients with type 2 diabetes mellitus in order to reduce the risk of long-term complications. Oral combination therapy that addresses insulin resistance and beta-cell dysfunction is a proven means of improving glycaemic control when monotherapy becomes insufficiently effective. Metformin/glibenclamide (glyburide) combination tablets were developed to provide a means of applying this strategy while minimising polypharmacy. This review examines the tolerability profile of this treatment from four double-blind, randomised clinical trials in a total of 2342 type 2 diabetic patients with hyperglycaemia despite treatment with diet and exercise, a sulphonylurea or metformin. Treatment with combination tablets was associated with markedly superior blood glucose control, at lower doses of metformin and glibenclamide, compared with monotherapies. The incidence of symptoms of hypoglycaemia varied between dosages and trials, though the incidence of severe or biochemically confirmed hypoglycaemia or withdrawals from clinical trials for this reason was consistently low and comparable with glibenclamide alone. No patient required third-party assistance for hypoglycaemia. Significantly fewer diet-failed patients receiving low-dose combination tablets reported gastrointestinal adverse effects compared with metformin alone, with a comparable incidence between metformin and combination tablets in post-monotherapy studies. The incidence of other adverse events, including serious adverse events, was similar for combination tablets and monotherapies. The lower doses of metformin and glibenclamide with the combination tablet approach, and the design of the combination tablets themselves, may underlie the beneficial tolerability profile of this treatment.

Modeling the efficiency of reaching a target intermediate end point: a case study in type 2 diabetes in the United States

OBJECTIVE

The objective of this study was to describe an approach to modeling the efficiency of an intervention by focusing on an established intermediate end point directly. A case study addresses the economic efficiency of obtaining dual glycemic control over time, according to initial choice of treatment.

METHODS

From the perspective of a payer in the United States, instead of the usual approach of basing the model on projecting long-term diabetic complications from glycemic control, this model focuses directly on glycemic control. Treatment changes and associated health-care utilization needed to address postprandial glucose. After assigning each of 10000 drug-naïve patients, HbA1c, age, race, and sex based on distributions from a randomized clinical trial, the model applies the efficacy of nateglinide compared to metformin. Sensitivity analyses were carried out for all parameters. Costs are reported in year 2000 US dollars and discounted at 3%.

RESULTS

In the base case, starting on nateglinide and increasing the time in dual glycemic control over 3 years by 2.4 months led to savings of US dollars 295 compared to starting on metformin. Savings increased with stricter treatment criteria but decreased if glycemic control was better initially.

CONCLUSIONS

This study illustrates the use of an efficiency model that focuses directly on the relevant short-term end point: glycemic control. Starting patients with nateglinide is shown to be an efficient way of obtaining dual glycemic control during the first 3 years of treatment.

Cardiovascular risk in type 2 diabetics and pharmacological regulation of mealtime glucose excursions

In type 2 diabetic patients mealtime glucose fluctuations are important determinants of overall glucose control and overall risk of diabetes cardiovascular complications. In fact, acute elevation of plasma glucose concentrations trigger an array of tissue response that may contribute to development of such vascular complications since it may result in a thrombophilic condition, causes endothelial dysfunction (possibly through a reduction of nitric oxide availability) and is responsible for non-enzymatic glycation and production of free- radicals with ensuing oxidative stress. To keep post-prandial glucose with narrow range, metiglinide analogues drugs have been developed. In particular, repaglinide and nateglinide seem the most useful ones. In fact, both drugs improve 1(st) phase insulin release but they do not affect the total daily amount of insulin released by the pancreas. Due to the mechanism of action and to pharmacokinetic properties, repaglinide and nateglinide allow diabetic patients to get a more tight metabolic glucose control with a contemporary reduction in the cases of severe hypoglycaemia. In conclusions, repaglinide and nateglinide are new and powerful pharmacological tools not only for achieving a better metabolic glucose control but also for preventing the development of diabetes-related cardiovascular complications.

The management of the obese diabetic patient

The prevalence of obesity and diabetes is increasing in the United States and worldwide. These diseases are predicted to explode to epidemic proportions, unless appropriate counteractive measures are taken. Several large studies (DCCT, UKPDS, Kumamoto) clearly showed that intensive glycemic control in the diabetic patient reduced microvascular complications and improved mortality. Despite this, the NHANES III showed that only 50% of diabetics have been able to achieve a HgbAic level that is less than 7%; this suggests the need for a re-evaluation of our approach to these patients. The management of the obese diabetic patient involves glycemic control and weight reduction. These goals are particularly difficult to achieve in the obese diabetic patient because progressive beta-cell dysfunction and increasing insulin resistance necessitates the administration of increasingly higher dosages of insulin, which, in turn, promotes weight gain. A vicious cycle may ensue. Lifestyle modifications with diet and exercise are an essential part of the management of the obese diabetic patient. These measures alone are often insufficient and concomitant pharmacologic therapy is usually required to achieve glycemic and weight control. Oral agents that improve glycemia, decrease insulin resistance, and limit weight gain are desirable. Because of the progressive nature of diabetes, glycemic control with monotherapy often deteriorates over time, which necessitates the addition of other pharmacologic agents, including insulin. When insulin therapy is required in the treatment of the obese diabetic patient, combinations with oral agents that have been shown to minimize the amount of exogenous insulin that is required, may minimize weight gain. In addition, the obese diabetic patient who is poorly controlled with maximum oral hypoglycemic therapy may benefit from weight-reducing agents, such as sibutramine or orlistat. The introduction of these agents at other points in the management of the obese diabetic patients have been successful. Finally, for the severely obese diabetic patient, bariatric surgery may be the only effective treatment. Gastric bypass has been unequivocally shown to produce significant weight loss and improve glycemic control on a long-term basis in the obese diabetic patient. It is recommended that physicians avail themselves of all of these strategies in the management of the obese patient who has type 2 diabetes.

The implementation of nutritional advice for people with diabetes

These consensus-based recommendations emphasize the practical implementation of nutritional advice for people with diabetes, and describe the provision of services required to provide the information. Important changes from previous recommendations include greater flexibility in the proportions of energy derived from carbohydrate and monounsaturated fat, further liberalization in the consumption of sucrose, more active promotion of foods with a low glycaemic index, and greater emphasis on the provision of nutritional advice in the context of wider lifestyle changes, particularly physical activity. Monounsaturated fats are now promoted as the main source of dietary fat because of their lower susceptibility to lipid peroxidation and consequent lower atherogenic potential. Consumption of sucrose for patients who are not overweight can be increased up to 10% of daily energy provided that this is eaten in the context of a healthy diet and distributed throughout the day [corrected]. Evidence is presented for the effectiveness of advice provided by trained dieticians. The increasing evidence for the importance of good metabolic control and the growing requirement for measures to prevent Type 2 diabetes in an increasingly obese population will require major expansion of dietetic services if the standards in National Service Frameworks are to be successfully implemented.

Effects of nateglinide on the secretion of glycated insulin and glucose tolerance in type 2 diabetes

AIMS

Glycation of insulin has been demonstrated within pancreatic beta-cells and the resulting impaired bioactivity may contribute to insulin resistance in diabetes. We used a novel radioimmunoassay to evaluate the effect of nateglinide on plasma concentrations of glycated insulin and glucose tolerance in type 2 diabetes.

METHODS

Ten patients (5 M/5 F, age 57.8+/-1.9 years, HbA(1c) 7.6+/-0.5%, fasting plasma glucose 9.4+/-1.2 mmol/l, creatinine 81.6+/-4.5 microM/l) received oral nateglinide 120 mg or placebo, 10 min prior to 75 g oral glucose in a random, single blind, crossover design, 1 week apart. Blood samples were taken for glycated insulin, glucose, insulin and C-peptide over 225 min.

RESULTS

Plasma glucose and glycated insulin responses were reduced by 9% (P=0.005) and 38% (P=0.047), respectively, following nateglinide compared with placebo. Corresponding AUC measures for insulin and C-peptide were enhanced by 36% (P=0.005) and 25% (P=0.007) by nateglinide.

CONCLUSIONS

Glycated insulin in type 2 diabetes is reduced in response to the insulin secretagogue nateglinide, resulting in preferential release of native insulin. Since glycated insulin exhibits impaired biological activity, reduced glycated insulin release may contribute to the antihyperglycaemic action of nateglinide.

Treatment of patients over 64 years of age with type 2 diabetes: experience from nateglinide pooled database retrospective analysis

OBJECTIVE

To evaluate the impact of renal impairment (RI) (estimated creatinine clearance [Cl(cr)] <60 ml/min per 1.73 m(2)) and low baseline HbA(1c) (<7.5%) on comorbidity in patients with type 2 diabetes, and to assess the efficacy and safety of nateglinide monotherapy in these patients and in subgroups of patients over age 64 years (elderly) and elderly with RI.

RESEARCH DESIGN AND METHODS

Retrospective subgroup analyses were performed on pooled data from all completed nateglinide studies (12 randomized, double blind trials and 1 open trial) in patients with type 2 diabetes. A total of 3,702 patients with > or =1 postbaseline safety evaluation received monotherapy with nateglinide (n = 2,204), metformin (n = 436), glyburide (n = 293), or placebo (n = 769). Efficacy (HbA(1c)) was evaluated in pooled data from four studies with similar design using 120 mg nateglinide (n = 544) versus placebo (n = 521). Evaluations were performed in the overall population and subgroups of patients over age 64 years. Specific considerations were given to RI, comorbidity, and baseline HbA(1c).

RESULTS

Patients over age 64 years (n = 1,170) represented 31.6% of the study population. Undiagnosed RI was common in the elderly with 83.4% of all patients being in this subgroup. Patients over 64 years with RI had a higher prevalence of cardio- and microvascular comorbidity compared with the overall population and all patients over age 64 years. Statistically significant HbA(1c) reductions versus placebo were observed with nateglinide in patients over age 64 years and elderly with RI patients at study end point (-0.9% and -1.1% in each subgroup, P < 0.01). Nateglinide was well tolerated with a low incidence of hypoglycemia in all subgroups, including those with RI and low baseline HbA(1c).

CONCLUSIONS

RI and comorbidity are common in patients over age 64 years with type 2 diabetes. Nateglinide was effective and well tolerated in all treated patients. In subgroups in which metformin and long-acting sulfonylureas must be used with caution, nateglinide had a low risk of adverse events and hypoglycemia.

Addition of nateglinide to rosiglitazone monotherapy suppresses mealtime hyperglycemia and improves overall glycemic control

OBJECTIVE

To determine the effects of nateglinide added to rosiglitazone monotherapy on glycemic control and on postprandial glucose and insulin levels in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This 24-week, multicenter, double-blind, randomized study compared the efficacy of nateglinide (120 mg a.c.) and placebo added to rosiglitazone monotherapy (8 mg q.d.) in 402 patients with type 2 diabetes with HbA(1c) between 7 and 11% (inclusive). Efficacy parameters tested included HbA(1c) and plasma glucose and insulin levels in the fasting state and after a standardized meal challenge. Safety data were also collected.

RESULTS

In placebo-treated patients, HbA(1c) did not change (Delta = 0.0 +/- 0.1%). In patients randomized to nateglinide, HbA(1c) decreased from 8.3 to 7.5% (Delta = -0.8 +/- 0.1%, P < 0.0001 vs. placebo). Target HbA(1c) (<7.0%) was achieved by 38% of patients treated with combination therapy and by 9% of patients remaining on rosiglitazone monotherapy. In nateglinide-treated patients, fasting plasma glucose levels decreased by 0.7 mmol/l, 2-h postprandial glucose levels decreased by 2.7 mmol/l, and 30-min insulin levels increased by 165 pmol/l compared with no changes from baseline of these parameters with placebo added to rosiglitazone (P < 0.001).

CONCLUSIONS

By selectively augmenting early insulin release and decreasing prandial glucose excursions, nateglinide produced a clinically meaningful improvement in overall glycemic exposure in patients with type 2 diabetes inadequately controlled with rosiglitazone. Therefore, nateglinide substantially improves the likelihood of achieving a therapeutic target of HbA(1c) <7.0%.

Pharmacological management of type 2 diabetes mellitus: rationale for rational use of insulin

Type 2 diabetes mellitus is a chronic metabolic disorder associated with high morbidity and mortality from long-term microvascular and macrovascular complications. Evidence from randomized controlled trials indicates that aggressive treatment directed at improving glycemic control reduces the incidence of diabetes-related microvascular complications. Traditionally, oral monotherapy for type 2 diabetes is initiated when diet and exercise do not control hyperglycemia, followed by the sequential, stepwise addition of oral agents as glycemic control deteriorates. Insulin is the last therapeutic option used, generally reserved for advanced stages of the disease when multiple oral combination treatment fails. Despite a better understanding of the pathophysiologic disease mechanisms in the past decade, the expanded armamentarium of targeted oral antidiabetic drugs, and the conclusive evidence of the benefits of stringent glycemic control, actual treatment outcomes in clinical practice remain suboptimal relative to established treatment goals (glycosylated hemoglobin A1c level <7%). Earlier detection and aggressive treatment are critical to address the natural progression of diabetes because multiple defects (insulin resistance, insulin insufficiency, glucotoxicity, and lipotoxicity) and vascular complications may be present at the time of diagnosis. Acknowledging the inadequacy of traditional strategies and underscoring the importance of insulin as an integral part of the therapeutic armamentarium, clinical trends are moving toward earlier use of insulin combined with 1 or more oral agents. Such strategies can address the multiple abnormalities present early in the disease course and may restore optimal control. A new treatment paradigm for patients with type 2 diabetes to achieve and maintain near-normal glycemic control is warranted.

Pharmacotherapy of diabetes mellitus: implications for the prevention and treatment of cardiovascular disease

Diabetes mellitus in adults is associated with an increased risk of premature vascular disease and a higher mortality rate. The presence of other risk factors, often seen in diabetic patients, such as systemic hypertension, augments the rate of vascular diseases. Evidence is growing that tight control of hyperglycemia using insulin and/or oral hypoglycemic agents will modify this risk. More aggressive control of concomitant hypertension and/or hyperlipidemia is also required. Diabetic patients who have myocardial infarctions do worse than nondiabetic patients. Various strategies to improve outcomes include the use of tight blood glucose control, and various coronary interventions are currently under clinical study.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A search was performed of the Cochrane Controlled Trials Register and the Database of Abstracts of Reviews of Effectiveness (up to 4/2000), Medline (up to 11/2000), Embase (up to 11/2000), Oldmedline, and Reactions (up to 5/2000), in order to identify all studies of metformin treatment from 1966 to November 2000. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: November 2000.

SELECTION CRITERIA

Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effects model for continuous data.

MAIN RESULTS

Pooled data from 176 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 35,619 patient-years of metformin use or in 30,002 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 8.4 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 9 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15).

REVIEWER'S CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions, taking into account contra-indications.

Nateglinide improves early insulin secretion and controls postprandial glucose excursions in a prediabetic population

OBJECTIVE

The purpose of this study was to evaluate the metabolic effectiveness, safety, and tolerability of nateglinide in subjects with impaired glucose tolerance (IGT) and to identify a dose appropriate for use in a diabetes prevention study.

RESEARCH DESIGN AND METHODS

This multicenter, double-blind, randomized, parallel-group, fixed-dose study of 8 weeks' duration was performed in a total of 288 subjects with IGT using a 2:2:2:1 randomization. Subjects received nateglinide (30, 60, and 120 mg) or placebo before each main meal. Metabolic effectiveness was assessed during a standardized meal challenge performed before and after the 8-week treatment. All adverse events (AEs) were recorded, and confirmed hypoglycemia was defined as symptoms accompanied by a self-monitoring of blood glucose measurement < or =3.3 mmol/l (plasma glucose < or =3.7 mmol/l).

RESULTS

Nateglinide elicited a dose-related increase of insulin and a decrease of glucose during standardized meal challenges, with the predominant effect on early insulin release, leading to a substantial reduction in peak plasma glucose levels. Nateglinide was well tolerated, and symptoms of hypoglycemia were the only treatment-emergent AEs. Confirmed hypoglycemia occurred in 28 subjects receiving nateglinide (30 mg, 0 [0%]; 60 mg, 5 [6.6%]; 120 mg, 23 [26.7%]) and in 1 (2.3%) subject receiving placebo.

CONCLUSIONS

Nateglinide was safe and effective in reducing postprandial hyperglycemia in subjects with IGT. Preprandial doses of 30 or 60 mg nateglinide would be appropriate to use for longer-term studies to determine whether a rapid-onset, rapidly reversible, insulinotropic agent can delay or prevent the development of type 2 diabetes.

Fasting and postchallenge glycemia and cardiovascular disease risk: the Framingham Offspring Study

OBJECTIVE

To test the hypothesis that fasting hyperglycemia (FHG) and 2-h postchallenge glycemia (2hPG) independently increase the risk for cardiovascular disease (CVD).

RESEARCH DESIGN AND METHODS

During 1991-1995, we examined 3,370 subjects from the Framingham Offspring Study who were free from clinical CVD (coronary heart disease, stroke, or intermittent claudication) or medication-treated diabetes, and we followed them for 4 years for incident CVD events. We used proportional-hazards regression to assess the risk associated with FHG (fasting plasma glucose > or =7.0 mmol/l) and 2hPG, independent of the risk predicted by standard CVD risk factors.

RESULTS

Mean subject age was 54 years, 54% were women, and previously undiagnosed diabetes was present in 3.2% by FHG and 4.9% (164) by FHG or a 2hPG > or =11.1 mmol/l. Of these 164 subjects, 55 (33.5%) had 2hPG > or =11.1 without FHG, but these 55 subjects represented only 1.7% of the 3,261 subjects without FHG. During 12,242 person-years of follow-up, there were 118 CVD events. In separate sex- and CVD risk-adjusted models, relative risk (RR) for CVD with fasting plasma glucose > or =7.0 mmol/l was 2.8 (95% CI 1.6-5.0); RR for CVD per 2.1 mmol/l increase in 2hPG was 1.2 (1.1-1.3). When modeled together, the RR for FHG decreased to 1.5 (0.7-3.6), whereas the RR for 2hPG remained significant (1.1, 1.02-1.3). The c-statistic for a model including CVD risk factors alone was 0.744; with addition of FHG, it was 0.746, and with FHG and 2hPG, it was 0.752.

CONCLUSIONS

Postchallenge hyperglycemia is an independent risk factor for CVD, but the marginal predictive value of 2hPG beyond knowledge of standard CVD risk factors is small.

Health and economic effects of adding nateglinide to metformin to achieve dual control of glycosylated hemoglobin and postprandial glucose levels in a model of type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus is a common disease whose complications have great costs, both in quality of life and expense of treatment. Improving glycemic control, as measured by monitoring glycosylated hemoglobin (HbA1c) levels, can reduce the rate of such complications.

OBJECTIVES

The aims of this study were to estimate the lifetime costs associated with diabetes-related complications in a theoretical population receiving metformin monotherapy and to predict the health and economic effect of improving glycemic control in this theoretical population by combining metformin with nateglinide.

METHODS

A pharmacoeconomic model was developed to simulate the long-term (30 years) complication rates (microvascular and macrovascular) of a cohort of patients with type 2 diabetes mellitus. The model simulated each year of life for each patient in a theoretical cohort of 10,000 patients until diabetes-related complications were present or death occurred. The mean accumulated costs (direct medical costs for acute care and subsequent care for diabetes-related complications), mean survival time, and the frequency of each type of complication were estimated. Both effectiveness and cost data were discounted at 3%. Sensitivity analyses were conducted on key model input parameters.

RESULTS

Average costs of treating complications in theoretical patients undergoing metformin monotherapy were estimated at $29,565 per patient. Savings of $2,742 were estimated per patient for all complications--particularly, nephropathy ($1,166) and macrovascular disease ($632)--when nateglinide was added. The cost-effectiveness ratio of adding nateglinide to metformin was estimated at $27,131 per undiscounted life-year gained (95% CI, $23,710-$28,577) or $43,024 (95% CI, $37,285-$45,193) per additional discounted life-year gained. In the sensitivity analyses, decreasing HbA1c level at baseline, HbA1c upward drift, and duration of disease improved survival.

CONCLUSIONS

Combination therapy with nateglinide and metformin, compared with metformin alone, was predicted to reduce the frequency of complications and, thus, treatment costs in this theoretical model. The major factor in cost savings was fewer complications due to nephropathy. The increased drug treatment costs were expected to be offset by the long-term savings from reducing complication rates.

Combination therapy with nateglinide and a thiazolidinedione improves glycemic control in type 2 diabetes

OBJECTIVE

To compare the effects of monotherapy using nateglinide and the thiazolidinedione troglitazone with initial combination of the two agents on glycated hemoglobin (HbA(1c)) in patients with type 2 diabetes inadequately controlled by diet alone.

RESEARCH DESIGN AND METHODS

This study consisted of a 28-week, double-blind, randomized, multicenter study that included a 4-week, single-blind, placebo, run-in period and a 24-week (shortened to 16 weeks), double-blind, active treatment period.

RESULTS

At the 16-week end point, nateglinide 120 mg, troglitazone 600 mg, and the combination of the agents achieved statistically significant decreases in HbA(1c) in comparison with placebo and a baseline HbA(1c) of 8.1-8.4% (P < 0.001). The reductions in HbA(1c) were similar in the nateglinide (0.6%) and troglitazone (0.8%) monotherapy groups. The reduction in HbA(1c) (1.7%) was greatest in the combination group; 79% of patients in the combination group achieved HbA(1c) levels of <7%. The combination group had a higher number of adverse events, primarily due to an increased incidence of mild hypoglycemia in this treatment group.

CONCLUSIONS

Nateglinide and troglitazone are equally effective in decreasing HbA(1c) levels. However, these reductions from baseline HbA(1c) values of >8% are not adequate to achieve HbA(1c) levels of <7%. In contrast, the combination of nateglinide and of a thiazolidinedione shows an additive effect that is highly effective in reducing HbA(1c) levels to the target of <7% in 66% of patients, from a baseline HbA(1c) that is just above 8%.

[Treatment of diabetes mellitus: general goals, and clinical practice management]

Diabetes mellitus is associated with a marked increased of cardiovascular events. The treatment strategy of diabetes has to be based on the knowledge of its pathophysiology. Thus, insulin is essential for treatment of type 1 diabetic patients because there is a defect in insulin secretion. However, treatment of type 2 diabetic patients is more complex because a defect in both insulin secretion and insulin action exists. Therefore, the treatment selection will depend on the stage of the disease and the individual characteristics of the patient. This article examines the general goals of the treatment and reviews the management of type 2 diabetes.

Current oral agents for type 2 diabetes. Many options, but which to choose when?

Increasingly, type 2 diabetes takes a toll on public health and healthcare costs in the United States. Although the remedy for this growing problem is very complex, two critical components of its control are prevention and effective therapy. Progress in diabetes prevention is likely to take decades. But fortunately, growth in our understanding of what occurs in this chronic disease has led to advances in the pharmacologic options aimed at decreasing hyperglycemia, the main clinically measurable metabolic consequence of diabetes. In this article, Drs Ahmann and Riddle provide an overview of the oral agents now available for the treatment of diabetes and discuss the clinical factors that help determine when to use which medication and what outcome to expect.

Nateglinide improves glycaemic control when added to metformin monotherapy: results of a randomized trial with type 2 diabetes patients

AIMS/HYPOTHESIS

This study evaluated the addition of nateglinide, a d-phenylalanine derivative that restores early phase insulin release, to metformin in type 2 diabetes patients stabilized on high-dose metformin.

METHODS

This multicentre, double-blind, parallel group trial included 467 metformin-treated patients with glycosylated haemoglobin (HbA1c) between 6.8% and 11%. Patients were randomized to add nateglinide 60 mg, 120 mg or placebo before three meals to metformin 1000 mg b.i.d. for 24 weeks.

RESULTS

HbA1c was significantly reduced with nateglinide 60 mg and 120 mg plus metformin compared with metformin control (-0.36%, p = 0.003; -0.59%, p < 0.001 respectively). Greater benefits occurred if patients had elevated HbA1c at baseline (-1.38% with nateglinide 120 mg in patients with HbA1c > 9.5%). A modest fasting plasma glucose reduction was observed. Most symptoms suggestive of hypoglycaemia occurred in patients with low HbA1c levels (<or= 8%) at baseline, although no confirmed cases of hypoglycaemia occurred with nateglinide 60 mg in this patient group. Events suggestive of hypoglycaemia were confirmed in 1.1% of cases (plasma glucose <or= 3.3 mmol/l). Weight gain over 24 weeks was 0.9 kg with nateglinide 120 mg vs. metformin alone, and plasma lipids remained unchanged.

CONCLUSIONS/INTERPRETATION

In patients stabilized on high-dose metformin, the addition of nateglinide improved glycaemic control. The combination of these agents was well tolerated and both doses of nateglinide proved effective. The efficacy of nateglinide 60 mg and the low rate of hypoglycaemia observed at this dose make it suitable for patients close to their therapeutic target on metformin monotherapy.

Dose-response effect of pioglitazone on insulin sensitivity and insulin secretion in type 2 diabetes

OBJECTIVE

To investigate the dose-response effects of pioglitazone on glycemic control, insulin sensitivity, and insulin secretion in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 58 diet-treated patients with type 2 diabetes (aged 54 +/- 1 years; 34 men and 24 women; BMI 31.5 +/- 0.6 kg/m(2)) were randomly assigned to receive placebo (n=11) or 7.5 mg (n=13), 15 mg (n=12), 30 mg (n=11), or 45 mg (n=11) of pioglitazone per day for 26 weeks. Before and after 26 weeks, subjects underwent a 75-g oral glucose tolerance test (OGTT).

RESULTS

Patients treated with 7.5 or 15 mg/day of pioglitazone had no change in fasting plasma glucose (FPG) and fasting plasma insulin (FPI) concentrations or in plasma glucose (PG) and insulin concentrations during the OGTT. Patients treated with 30 and 45 mg/day of pioglitazone, respectively, had significant decreases from placebo in HbA1c (delta=-2.0 and -2.9%), FPG (delta=-66 and -97 mg/dl), and mean PG during OGTT (delta=-84 and -107 mg/dl). Fasting plasma insulin decreased significantly in the 45-mg/day pioglitazone group, but the mean plasma insulin during the OGTT did not change. The insulinogenic index (delta area under the curve [AUC] insulin/deltaAUC glucose) during the OGTT increased significantly in the 30- and 45-mg/day pioglitazone groups (0.13 +/- 0.03 to 0.27 +/- 0.05, P < 0.05). From the OGTT, we previously have derived a composite whole-body insulin sensitivity index (ISI) that correlates well with that measured directly with the insulin clamp technique. Whole-body ISI [ISI=10,000/(square-root (FPG x FPI) x (PG x PI)) where PG and PI equal mean plasma glucose and insulin concentrations during OGTT] increased significantly in patients treated with 30 mg (1.8 +/- 0.3 to 2.5 +/- 0.3, P < 0.05) or 45 mg (1.6 +/- 0.2 to 2.7 +/- 0.6, P < 0.05) per day of pioglitazone. In the basal state, the hepatic ISI [k/(FPG x FPI)[k/(FPG x FPI)], which agrees closely with that measured directly with tritiated glucose, increased in patients treated with 30 mg (0.13 +/- 0.02 to 0.21 +/- 0.03, P < 0.05) and 45 mg (0.11 +/- 0.02 to 0.24 +/- 0.06, P < 0.05) per day of pioglitazone. Significant correlations between the dose of pioglitazone and the changes in HbA1c (r=-0.58), FPG (r=-0.47), mean PG during the OGTT (r=-0.46), insulinogenic index (r=0.34), hepatic ISI (r=0.44), and whole-body ISI (r=0.36) were observed.

CONCLUSIONS

Pioglitazone improves glycemic control through the dose-dependent enhancement of beta-cell function and improved whole-body and hepatic insulin sensitivity.

Restoring post-prandial insulin release in type 2 diabetes

Tight blood glucose control is a primary aim of type 2 diabetes treatment. Combining metformin with the amino acid derivative, nateglinide, tackles both beta cell dysfunction and insulin resistance, and produces a greater decrease in haemoglobin A1c levels than treatment with either drug alone.

Insulin secretagogues

Existing oral insulin secretagogues, sulphonylureas, are associated with hyperinsulinaemia, risk of hypoglycaemia and weight gain. Furthermore, they are not able to offer durable glycaemic control in patents with type 2 diabetes and are associated with progressive decline of beta-cell function. New insulin secretagogues offer an exciting opportunity. Repaglinide, the first prandial glucose regulator, now has convincing data that, compared to sulphonylurea use, it has a lower risk of hypoglycaemia. When used in a flexible dosing regime in a large cohort of patients, it is associated with better glycaemic control, a reduction in HbA1c, weight loss and improved quality of life compared to sulphonylureas. Early data shows the possibility of an effective combination with night time isophane insulin with significant falls in HbA1c and lower doses of insulin required. Nateglinide is an amino acid derivative. It again acts directly on the pancreatic beta-cell. Because of its very short duration of action, and the fact that it appears to secrete insulin in a glucose-dependent manner, it appears to secrete insulin in the closest way to that seen in a person without diabetes. Early data, both in monotherapy and in combination with metformin, show that it is an effective agent in terms of lowering HbA1c, has a low risk of hypoglycaemia and potentially less risk of significant weight gain. These characteristics mean that it may be the ideal agent to be used very early in the disease process, or even in subjects with impaired glucose tolerance, in whom early-phase insulin response is already lost. However these concepts, at the present time, are unproven.

Treatment of type 2 diabetes mellitus: pharmacologic intervention

Since 1995 there have been several new medications approved for the treatment of type 2 diabetes. The availability of these new medications has made the treatment regiment for type 2 diabetes complex. There are currently five classes of oral antidiabetic agents available in the United States. These classes include: sulfonylureas, meglitinides, alpha-glucosidase inhibitors, thiazolidinediones, and biguanides. Additionally there are several types of insulin and insulin analogs available for the treatment of hyperglycemia: regular, lispro, aspart, NPH, lente, ultralente, glargine, 70/30, 50/50, and 75/25. In this article, the mechanism, site of action, and adverse effects of these classes will be reviewed. The efficacy and important management issues of these glucose-lowering drugs used in monotherapy and in combination will be discussed.

Oral therapies for diabetic hyperglycemia

Many classes of oral antihyperglycemic agents are available for the treatment of type 2 diabetic patients. These classes improve glucose metabolism by different mechanisms, and their effects are additive. Therapy with lifestyle modification and a single oral antihyperglycemic agent infrequently achieves target glycemic goals, and, if it does, the effect is usually not sustained. A more rational approach would seem to be therapy with combinations of drugs with different mechanisms of action. Initial therapy might be with submaximal concentrations of two drugs. As the diabetic abnormalities progress, maximal concentrations of the drugs and addition of other classes of oral agents or insulin may be needed to maintain the target glycemic goal. In choosing combinations of oral antihyperglycemic agents, their effects on the components treatment of type 2 diabetic patients. These classes improve glucose considered, as must the specific effects of the agents on glucose metabolism.

Insulinotropic meglitinide analogues

The loss of early-phase insulin secretion is an important and early event in the natural history of type 2 diabetes. Because a normal pattern of insulin secretion is essential for the effective control of postprandial metabolism, a rational basis for the development of agents that target early-phase insulin release exists. Conventional oral hypoglycaemic agents do not target, or adequately control, postprandial glycaemia. The emergence of new classes of oral agent with a more specific mode of action provides, for the first time, an opportunity to restore early-phase insulin release. One such drug class is the meglitinide analogues (repaglinide, nateglinide, and mitiglinide). These drugs are ideally suited for combination use with metformin. They could also prove effective in combination with a thiazolidinedione, a drug class that targets insulin resistance. Exogenous insulin is frequently required in the late management of type 2 diabetes. However, one hope for newer combinations of diabetic drugs is that the functional life of the beta cell can be extended, thereby delaying the need for insulin injections.

Recent developments in the management of type 2 diabetes

Type 2 diabetes is a common, chronic disease, with a high risk of macrovascular and microvascular complications that lead to premature death and disability. The disease is managed largely in primary care and its rising prevalence will increase the workload of community nurses. The forthcoming Diabetes National Service Framework will aim to improve the standards of diabetic care, while scientific and technological developments offer new treatments that may also improve the outlook for patients. There is as yet no case for population screening for type 2 diabetes, but community nurses are ideally placed to carry out local screening initiatives based on consensus guidelines.

Nateglinide therapy for type 2 diabetes mellitus

OBJECTIVE

To review the pharmacology, pharmacokinetics, dosing guidelines, adverse effects, drug interactions, and clinical efficacy of nateglinide.

DATA SOURCES

Primary and review articles regarding nateglinide were identified by MEDLINE search (from 1966 to January 2001); abstracts were identified through the Institute for Scientific Information Web of Science (from 1995 to January 2001) and the American Diabetes Association; additional information was obtained from the nateglinide product information.

STUDY SELECTION/DATA EXTRACTION

All articles and meeting abstracts identified from the data sources were evaluated and all information deemed relevant was included in this review. Much of the information was from abstracts or the product labeling, since few clinical studies have been published in the medical literature.

DATA SYNTHESIS

Nateglinide is a novel nonsulfonylurea oral antidiabetic agent that stimulates insulin secretion from the pancreas. It has a rapid onset and short duration of action, allowing administration before a meal to reduce postprandial hyperglycemia. Improvement in glycemic control with nateglinide monotherapy has been demonstrated in patients not previously treated with antidiabetic medications. Greater improvement in glycemic control was observed when nateglinide was administered in combination with metformin.

CONCLUSIONS

Nateglinide is similar to repaglinide, but has a quicker onset of action, quicker reversal, and does not usually require dosage titration. Based on the pharmacodynamics of nateglinide and repaglinide, nateglinide produces a more rapid postprandial increase in insulin secretion, and its duration of response is shorter than that of repaglinide. The risk of postabsorptive hypoglycemia should be lower than with either sulfonylureas or repaglinide.

Postchallenge hyperglycemia in a national sample of U.S. adults with type 2 diabetes

OBJECTIVE

Postchallenge hyperglycemia (PCH) is known to contribute to suboptimal glycemic control in adults with non-insulin-requiring type 2 diabetes. The objective of this study was to estimate the prevalence of PCH among individuals with diabetes.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional analysis of data from the Third National Health and Nutrition Examination Survey (1988-1994) in adults aged 40-74 years with diabetes who were not using insulin (i.e., they used oral hypoglycemics or received no pharmacological therapy). Each respondent underwent a standard 75-g oral glucose tolerance test. PCH was defined as a 2-h glucose level >or=200 mg/dl.

RESULTS

Overall, PCH was present in 74% of those with diagnosed diabetes. Although it was present in virtually all (99%) of the diabetic adults under suboptimal glycemic control (HbA(1c) >or=7.0%), PCH was also common (39%) among those under optimal control (HbA(1c) <7.0%). Likewise, among sulfonylurea users, PCH was present in 99% of those under suboptimal control and in 63% of those under good control. Similar patterns were observed in those with undiagnosed diabetes. Isolated PCH (2-h glucose >or=200 mg/dl and fasting glucose <126 mg/dl) was present in 9.8% of the adults with diagnosed diabetes.

CONCLUSIONS

These data suggest that PCH is common among diabetic adults in the U.S., even in the setting of "optimal" glycemic control and sulfonylurea use. Interventions designed to lower postprandial glucose excursions may help improve overall glycemic control in the general population of U.S. adults with diabetes.

Importance of early insulin secretion: comparison of nateglinide and glyburide in previously diet-treated patients with type 2 diabetes

OBJECTIVE

This study compared the effects of nateglinide, glyburide, and placebo on postmeal glucose excursions and insulin secretion in previously diet-treated patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This randomized, double-blind, placebo-controlled multicenter study was conducted in 152 patients who received either nateglinide (120 mg before three meals daily, n = 51), glyburide (5 mg q.d. titrated to 10 mg q.d. after 2 weeks, n = 50), or placebo (n = 51) for 8 weeks. Glucose, insulin, and C-peptide profiles during liquid meal challenges were measured at weeks 0 and 8. At weeks -1 and 7, 19-point daytime glucose and insulin profiles, comprising three solid meals, were measured.

RESULTS

During the liquid-meal challenge, nateglinide reduced the incremental glucose area under the curve (AUC) more effectively than glyburide ( = -4.94 vs. -2.71 mmol. h/l, P < 0.05), whereas glyburide reduced fasting plasma glucose more effectively than nateglinide ( = -2.9 vs. -1.0 mmol/l, respectively, P < 0.001). In contrast, C-peptide induced by glyburide was greater than that induced by nateglinide ( = +1.83 vs. +0.95 nmol. h/l, P < 0.01), and only glyburide increased fasting insulin levels. During the solid meal challenges, nateglinide and glyburide elicited similar overall glucose control ( 12-h incremental AUC = -13.2 vs. -15.3 mmol. h/l), but the insulin AUC induced by nateglinide was significantly less than that induced by glyburide ( 12-h AUC = +866 vs. +1,702 pmol. h/l, P = 0.01).

CONCLUSIONS

This study demonstrated that nateglinide selectively enhanced early insulin release and provided better mealtime glucose control with less total insulin exposure than glyburide.

Nateglinide

Nateglinide is a novel D-phenylalanine derivative that inhibits ATP-sensitive K+ channels in pancreatic beta-cells in the presence of glucose and thereby stimulates the prandial release of insulin. Nateglinide reduces fasting and mealtime blood glucose levels in animals, healthy volunteers, and patients with type 2 (non-insulin-dependent) diabetes mellitus, and produces prompt prandial insulin responses with return to baseline insulin levels between meals. In randomised, double-blind 24-week studies in patients with type 2 diabetes, oral nateglinide 120 mg 3 times daily before meals improved glycaemic control significantly relative to placebo. Nateglinide 120 mg plus metformin 500 mg, both 3 times daily, conferred greater glycaemic improvement than either drug given alone, and nateglinide 60 or 120 mg 3 times daily plus metformin 1 g twice daily was superior to metformin plus placebo. Nateglinide 120 mg 3 times daily significantly reduced hyperglycaemia relative to placebo in a 16-week double-blind study in patients with type 2 diabetes mellitus. Combination therapy with troglitazone 600 mg daily produced significantly better glycaemic control than either drug given as monotherapy. Mild hypoglycaemia was the most frequently reported adverse event (1.3% of patients) after treatment with nateglinide 120 mg 3 times daily in a 16-week clinical study. No clinically significant abnormalities in laboratory results, ECGs, vital signs or physical examination findings have been noted in patients taking the drug.