The NEPI antidiabetes study (NANSY). 1: short-term dose-effect relations of glimepiride in subjects with impaired fasting glucose

Insulin secretagogues for prevention or delay of type 2 diabetes mellitus and its associated complications in persons at increased risk for the development of type 2 diabetes mellitus

BACKGROUND

The projected rise in the incidence of type 2 diabetes mellitus (T2DM) could develop into a substantial health problem worldwide. Whether insulin secretagogues (sulphonylureas and meglitinide analogues) are able to prevent or delay T2DM and its associated complications in people at risk for the development of T2DM is unknown.

OBJECTIVES

To assess the effects of insulin secretagogues on the prevention or delay of T2DM and its associated complications in people with impaired glucose tolerance, impaired fasting blood glucose, moderately elevated glycosylated haemoglobin A1c (HbA1c) or any combination of these.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, and the reference lists of systematic reviews, articles and health technology assessment reports. We asked investigators of the included trials for information about additional trials. The date of the last search of all databases was April 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with a duration of 12 weeks or more comparing insulin secretagogues with any pharmacological glucose-lowering intervention, behaviour-changing intervention, placebo or no intervention in people with impaired fasting glucose, impaired glucose tolerance, moderately elevated HbA1c or combinations of these.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles/records, assessed quality and extracted outcome data independently. One review author extracted data which were checked by a second review author. We resolved discrepancies by consensus or the involvement of a third review author. For meta-analyses we used a random-effects model with investigation of risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We carried out trial sequential analyses (TSAs) for all outcomes that could be meta-analysed. We assessed the overall quality of the evidence by using the GRADE instrument.

MAIN RESULTS

We included six RCTs with 10,018 participants; 4791 participants with data on allocation to intervention groups were randomised to a second- or third-generation sulphonylurea or a meglitinide analogue as monotherapy and 29 participants were randomised to a second-generation sulphonylurea plus metformin. Three trials investigated a second-generation sulphonylurea, two trials investigated a third-generation sulphonylurea and one trial a meglitinide analogue. A total of 4873 participants with data on allocation to control groups were randomised to a comparator group; 4820 participants were randomised to placebo, 23 to diet and exercise, and 30 participants to metformin monotherapy. One RCT of nateglinide contributed 95% of all participants. The duration of the intervention varied from six months to five years. We judged none of the included trials as at low risk of bias for all 'Risk of bias' domains.All-cause and cardiovascular mortality following sulphonylurea (glimepiride) treatment were rarely observed (very low-quality evidence). The RR for incidence of T2DM comparing glimepiride monotherapy with placebo was 0.75; 95% CI 0.54 to 1.04; P = 0.08; 2 trials; 307 participants; very low-quality evidence. One of the trials reporting on the incidence of T2DM did not define the diagnostic criteria used. The other trial diagnosed T2DM as two consecutive fasting blood glucose values ≥ 6.1 mmol/L. TSA showed that only 4.5% of the diversity-adjusted required information size was accrued so far. No trial reported data on serious adverse events, non-fatal myocardial infarction (MI), non-fatal stroke, congestive heart failure (HF), health-related quality of life or socioeconomic effects.One trial with a follow-up of five years compared a meglitinide analogue (nateglinide) with placebo. A total of 310/4645 (6.7%) participants allocated to nateglinide died compared with 312/4661 (6.7%) participants allocated to placebo (hazard ratio (HR) 1.00; 95% CI 0.85 to 1.17; P = 0.98; moderate-quality evidence). The two main criteria for diagnosing T2DM were a fasting plasma glucose level ≥ 7.0 mmol/L or a 2-hour post challenge glucose ≥ 11.1 mmol/L. T2DM developed in 1674/4645 (36.0%) participants in the nateglinide group and in 1580/4661 (33.9%) in the placebo group (HR 1.07; 95% CI 1.00 to 1.15; P = 0.05; moderate-quality evidence). One or more serious adverse event was reported in 2066/4602 (44.9%) participants allocated to nateglinide compared with 2089/4599 (45.6%) participants allocated to placebo. A total of 126/4645 (2.7%) participants allocated to nateglinide died because of cardiovascular disease compared with 118/4661 (2.5%) participants allocated to placebo (HR 1.07; 95% CI 0.83 to 1.38; P = 0.60; moderate-quality evidence). Comparing participants receiving nateglinide with those receiving placebo for the outcomes MI, non-fatal stroke and HF gave the following event rates: MI 116/4645 (2.5%) versus 122/4661 (2.6%), stroke 100/4645 (2.2%) versus 110/4661 (2.4%) and numbers hospitalised for HF 85/4645 (1.8%) versus 100/4661 (2.1%) - (HR 0.85; 95% CI 0.64 to 1.14; P = 0.27). The quality of the evidence was moderate for all these outcomes. Health-related quality of life or socioeconomic effects were not reported.

AUTHORS' CONCLUSIONS

There is insufficient evidence to demonstrate whether insulin secretagogues compared mainly with placebo reduce the risk of developing T2DM and its associated complications in people at increased risk for the development of T2DM. Most trials did not investigate patient-important outcomes.

Can sulphonylurea addition to lifestyle changes help to delay diabetes development in subjects with impaired fasting glucose? The Nepi ANtidiabetes StudY (NANSY)

The Nepi ANtidiabetes StudY (NANSY) is a 5-year randomized, double-blind, placebo-controlled trial in Swedish primary care, examining whether the development of type 2 diabetes (T2D) and retinopathy (separately reported) would be delayed in 40- to 70-year-old subjects with impaired fasting glucose (IFG) who, in addition to lifestyle changes, were treated with either placebo or low-dosage sulphonylurea (SU) (1-mg glimepiride; Amaryl). Of 274 subjects (163 men, 111 women), 138 were allocated to placebo (46.0% men, 56.8% women) and 136 to glimepiride (54.0% men, 43.2% women). The primary endpoint was conversion to diabetes. Average follow-up time was 3.71 years; 96 subjects converted to diabetes, 55 allocated to placebo and 41 to glimepiride (absolute difference 9.8%; p = 0.072). In conclusion, the study failed to support the notion that low-dose SU added to lifestyle changes in IFG subjects would help to delay the conversion to diabetes.

Oxidative stress and beta-cell dysfunction

Diabetes mellitus type 1 and 2 (T1DM and T2DM) are complex multifactorial diseases. Loss of beta-cell function caused by reduced secretory capacity and enhanced apoptosis is a key event in the pathogenesis of both diabetes types. Oxidative stress induced by reactive oxygen and nitrogen species is critically involved in the impairment of beta-cell function during the development of diabetes. Because of their low antioxidant capacity, beta-cells are extremely sensitive towards oxidative stress. In beta-cells, important targets for an oxidant insult are cell metabolism and K(ATP) channels. The oxidant-evoked alterations of K(ATP) channel activity seem to be critical for oxidant-induced dysfunction because genetic ablation of K(ATP) channels attenuates the effects of oxidative stress on beta-cell function. Besides the effects on metabolism, interference of oxidants with mitochondria induces key events in apoptosis. Consequently, increasing antioxidant defence is a promising strategy to delay beta cell failure in (pre)-diabetic patients or during islet transplantation. Knock-out of K(ATP) channels has beneficial effects on oxidant-induced inhibition of insulin secretion and cell death. Interestingly, these effects can be mimicked by sulfonylureas that have been used in the treatment of T2DM for many years. Loss of functional K(ATP) channels leads to up-regulation of antioxidant enzymes, a process that depends on cytosolic Ca(2+). These observations are of great importance for clinical intervention because they show a possibility to protect beta-cells at an early stage before dramatic changes of the secretory capacity and loss of cell mass become manifest and lead to glucose intolerance or even overt diabetes.

A small-molecule glucokinase activator lowers blood glucose in the sulfonylurea-desensitized rat

Glucokinase activators increase insulin release from pancreatic beta-cells and hepatic glucose utilization by modifying the activity of glucokinase, a key enzyme in glucose-sensing and glycemic regulation. Sulfonylureas are antihyperglycemic agents that stimulate insulin secretion via a glucose-independent mechanism that is vulnerable to secondary failure through beta-cell desensitization. The present study determined whether glucokinase activator treatment retains its glucose-lowering efficacy in male, adult, non-diabetic Sprague-Dawley rats desensitized to sulfonylurea treatment and whether glucose-lowering during chronic glucokinase activator treatment is subject to secondary failure. Animals were given food containing either glimepiride (a sulfonylurea), Compound B (3-[(1S)-2-hydroxy-1-methylethoxy]-5-[4-(methylsulfonyl)phenoxy]-N-1,3-thiazol-2-ylbenzamide, an experimental glucokinase activator), or no drug for up to 5 weeks. Food containing 0.04% of either drug produced acute (within 4-8 h) and significant (P<0.05) reductions in blood glucose to approximately 50% of control levels. Chronic treatment with either 0.01% or 0.04% glimepiride resulted in complete failure of glucose-lowering efficacy within 3 days whereas the efficacy of Compound B was sustained throughout the entire study. Glipizide, also a sulfonylurea, had no glucose-lowering effect when given by gavage (3mg/kg) to glimepiride-desensitized animals whereas Compound B retained full glucose-lowering efficacy in glimepiride-desensitized animals. Oral glucose tolerance was significantly impaired, compared with controls, in animals treated with glimepiride for two weeks but was enhanced to a small extent in animals treated with Compound B. Compound B also significantly increased pancreatic insulin content, compared with controls. These findings suggest that Compound B has sustained glucose-lowering effects in a rat model of sulfonylurea failure.

Retinopathy in subjects with impaired fasting glucose: the NANSY-Eye baseline report

AIMS

Network for Pharmacoepidemiology (NEPI) Antidiabetes Study-Eye is a randomized placebo-controlled Swedish trial investigating if treatment with sulphonylurea, in addition to dietary regulation and increased exercise, delays the development of retinopathy in subjects with impaired fasting glucose (IFG).

METHODS

Subjects were surveyed in primary care with repeated fasting blood glucose measurements. Those with a mean of two consecutive values >or=5.6 and <6.1 mmol/l were invited to participate. Baseline physical examination included blood pressure and body mass index (BMI). Fundus photos were taken in two fields using 35-mm diafilm. The alternative classification of the Wisconsin Epidemiologic Study of Diabetic Retinopathy was used to classify the retinopathy level.

RESULTS

At baseline, 90 men and 64 women with IFG were photographed. Of these, 16 subjects (10%) had mild or very mild retinopathy. There was no difference in occurrence of retinopathy between subjects with known diagnosis of hypertension or not. However, subjects with retinopathy had significantly higher systolic (154 vs. 141 mmHg, p = 0.013) and diastolic (86 vs. 81 mmHg, p = 0.008) blood pressure levels independent of differences in age, sex and known hypertension. There was a corresponding difference in BMI, being greater in subjects with than in those without retinopathy (32.4 vs. 29.2 kg/m(2), p = 0.013). There were no associations between levels of fasting blood glucose or haemoglobin A1c, on the one hand, and retinopathy, on the other.

CONCLUSION

Retinopathy may be present even before type 2 diabetes is manifest. It is associated with higher blood pressure levels and higher BMI values, that is, with predominant features of the metabolic syndrome.

Antidiabetic agents in subjects with mild dysglycaemia: prevention or early treatment of type 2 diabetes?

Besides lifestyle, various pharmacological treatments have proven their efficacy to reduce the incidence of type 2 diabetes in high-risk individuals, especially in those with impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG). Major placebo-controlled clinical trials demonstrated favourable effects of various glucose-lowering drugs generally used for the treatment of type 2 diabetes, i.e. metformin, acarbose and thiazolidinediones (glitazones). These trials showed a lower rate of progression to overt diabetes and a higher regression rate to a normal glucose status with active treatment as compared to placebo after a follow up of several years. Ongoing trials should confirm such a favourable effect with those drugs and may demonstrate a similar protective effect with other pharmacological approaches such as glinides or even basal insulin regimen. However, the reported favourable effects were generally observed while the subjects were still on treatment, and partially vanished after a rather short period of wash-out of several weeks. Therefore, the distinction between a true preventing effect and simply a masking effect is difficult with glucose-lowering drugs. In addition, as type 2 diabetes is a progressive disease, it is still questionable whether the effect corresponds to a prevention effect or only to a postponing of the development of the disease. Owing to the pathophysiology of the disease, the only way to block the progression of type 2 diabetes is probably to avoid the progressive loss of beta-cell function and/or mass. Whatsoever, these data obtained in large clinical trials bring further argument to support early treatment of diabetes, even at a prediabetic state, in order to stop the vicious circle leading to an inevitable deterioration of glycaemia in predisposed subjects.

A systematic review of drug therapy to delay or prevent type 2 diabetes

OBJECTIVE

To systematically review the evidence for the prevention of type 2 diabetes by pharmacological therapies.

RESEARCH DESIGN AND METHODS

Randomized controlled trials and cohort studies examining the effect of oral hypoglycemic agents, antiobesity agents, antihypertensive agents, statins, fibrates, and estrogen on the incidence of type 2 diabetes were identified from MEDLINE, EMBASE, the Cochrane Controlled Trials Registry, and searches of reference lists. Two reviewers independently assessed studies for inclusion and performed data extraction.

RESULTS

Ten studies of oral hypoglycemic agents and 15 studies of nonoral hypoglycemic agents were found. Oral hypoglycemic agents and orlistat are the only drugs that have been studied in randomized controlled trials with diabetes incidence as the primary end point. In the largest studies of 2.5-4.0 years' duration, metformin (relative risk [RR] 0.69, 95% CI 0.57-0.83), acarbose (0.75, 0.63-0.90), troglitazone (0.45, 0.25-0.83), and orlistat (hazard ratio [HR] 0.63, 95% CI 0.46-0.86) have all been shown to decrease diabetes incidence compared with placebo; however, follow-up rates varied from 43 to 96%. Current evidence for statins, fibrates, antihypertensive agents, and estrogen is inconclusive. In addition, the critical question of whether drugs are preventing, or simply delaying, onset of diabetes remains unresolved.

CONCLUSIONS

Currently, no single agent can be definitively recommended for diabetes prevention. Future studies should be designed with diabetes incidence as the primary outcome and should be of sufficient duration to differentiate between genuine diabetes prevention as opposed to simple delay or masking of this condition.

Kinetics-effect relations of insulin-releasing drugs in patients with type 2 diabetes: brief overview

Sulfonylureas and glinides have similar mechanisms of action but differ in receptor affinity and binding sites and in absorption and elimination rates. This promotes differences in potency, rate of onset, and duration of action. While prominent in single-dose studies, these differences have less importance during long-term sulfonylurea treatment: at ordinary dosages, rapid- and short-acting (glipizide) and slow- and long-acting (glyburide) sulfonylureas maintained continuously effective plasma levels and similar 24-h glucose control. Moreover, there was no difference in patient outcome between the first-generation sulfonylurea chlorpropamide and the second-generation glyburide in the U.K. Prospective Diabetes Study. However, the risk of long-lasting and hence dangerous hypoglycemia is higher with these two long-acting sulfonylureas. Conversely, this risk should be low with the short-acting glinides, but seemingly at the expense of less effective glucose control. The most important kinetics-effect relations are that hyperglycemia delays sulfonylurea absorption and that the sulfonylurea dose-response curve is bell shaped; continuous sulfonylurea exposure over a certain level (e.g., 10 mg glipizide) impairs rather than improves insulin and glucose responses to sulfonylurea (downregulation). Accordingly, a vicious circle may be established: unrelenting hyperglycemia may promote sulfonylurea dose increase, which increases hyperglycemia, promoting further dose increase and eventually therapeutic failure.

Low-dose oral glyburide reduces glucose production rates in patients with impaired fasting glucose

Impaired fasting glucose (IFG) is commonly seen in the US population. Approximately 20% of patients with IFG can progress to develop type 2 diabetes mellitus (DM-2) within 1 year. In the recent diabetes prevention study, lifestyle changes reduced the progression to only 8% per year, and metformin reduced the progression from IFG to DM-2 from 20% to 11% per year. Sulfonylurea therapy in DM-2 increases beta-cell function and fails to accelerate the 4% loss in function observed per year. Low-dose sulfonylurea therapy for IFG may be an effective treatment to delay the onset of type 2 diabetes if the treatment does not cause hypoglycemia. A very low dose of glyburide (20 microg/kg body weight) was given orally to 15 nondiabetic volunteers in an attempt to describe its effects on glucose production rates (GPR), blood glucose concentrations, and conterregulatory hormone profile. Six of the volunteers had IFG (mean +/- SEM, 115 +/- 1.8 mg/dL), and 9 had a normal fasting glucose (NFG) (94 +/- 2.3 mg/dL). Fasting blood glucose (FBG) decreased more in IFG after glyburide when compared with the NFG group (29% +/- 2.4% v 17% +/- 3.5%, P <.05). Patients with IFG had a larger insulin response to glyburide than those with NFG (17.7 +/-3 v 10.7 +/- 2.9 microU/mL; P <.05). The IFG patients also had a greater decrease in GPR (19% +/- 4%) than seen with the normals (12% +/- 3%, P <.05). The steeper decrease in GPR may have been due to a greater insulin response to oral glyburide in those with IFG. Low-dose glyburide increases insulin's effect on the liver.