Secondary sulfonylurea failure: comparison of period until insulin treatment between diabetic patients treated with gliclazide and glibenclamide

Current Position of Gliclazide and Sulfonylureas in the Contemporary Treatment Paradigm for Type 2 Diabetes: A Scoping Review

The increasing burden of type 2 diabetes (T2D), in relation to alarming rise in the prevalence; challenges in the diagnosis, prevention, and treatment; as well as the substantial impact of disease on longevity and quality of life, is a major concern in healthcare worldwide. Sulfonylureas (SUs) have been a cornerstone of T2D pharmacotherapy for over 60 years as oral antidiabetic drugs (OADs), while the newer generation SUs, such as gliclazide modified release (MR), are known to be associated with low risk of hypoglycemia in addition to the cardiovascular neutrality. This scoping review aimed to specifically address the current position of gliclazide MR among other SUs in the contemporary treatment paradigm for T2D and to provide a practical guidance document to assist clinicians in using gliclazide MR in real-life clinical practice. The main topics addressed in this paper include the role of early and sustained glycemic control and use of SUs in T2D management, the properties of gliclazide MR in relation to its effectiveness and safety, the use of gliclazide therapy in special populations, and the place of SUs as a class and gliclazide MR specifically in the current T2D treatment algorithm.

Profiles of sulfonylurea use in Diabetes Mellitus type 2: an analysis of clinical practice over the last 10 years

AIMS

Describing the evolution over time in the use of sulfonylureas (SUs) and the characteristics of patients at first prescription and at interruption of treatment with SUs.

METHODS

Retrospective evaluation of data from the Italian Association of Diabetologists (AMD) Annals registry (2010-2020), about T2D patients who started treatment with SUs. The longitudinal probability of remaining on SUs was estimated by Kaplan Meier survival curves.

RESULTS

SU prescription decreased from 30.7 % (2010) to 12.9 % (2020). Patients started on SU were 68.2 ± 11.2 years old, mostly males (55.5 %), with diabetes duration = 10.1 ± 8.3 years, BMI = 29.7 ± 5.5 kg/m2, and HbA1c = 8.3 ± 1.7 % [67 mmol/mol]. After one year, the probability of staying on SU was 85.4 %, 75.9 % after two years, 68.2 % after 3 years, 56.6 % after 5 years. Patients who discontinued SUs had higher BMI and HbA1c, were younger, more often males and treated with insulin. Over time, the percentage of subjects switched to metformin, DPP4i, SGLT2i, and GLP1RA increased, whereas use of glinides, glitazones, acarbose and insulin declined.

CONCLUSIONS

These data suggest a consensus, slowly, but increasingly aligning with the current National indications of dismissing SUs for the treatment of T2D. The new drugs for diabetes should represent a preferable choice in all patients who do not have specific contraindications.

The role of sulfonylureas in the treatment of type 2 diabetes

INTRODUCTION

Type 2 diabetes (T2D) is increasingly prevalent and associated with increased risk for cardiovascular and renal disease. After lifestyle modification, metformin is usually the first-line pharmacotherapy and sulfonylureas are traditionally added after metformin failure. However, with newer glucose lowering drugs that may have less risk of hypoglycemia or that may reduce cardiovascular and renal events, the position of sulfonylureas is being reevaluated.

AREAS COVERED

In this article, the authors review relevant publications related to the use of sulfonylureas.

EXPERT OPINION

Sulfonylureas are potent glucose lowering drugs. The risk of hypoglycemia varies with different drugs within the class and can be minimized by using the safer drugs, possibly in lower doses. Cardiovascular events do not appear to be increased with some of the newer generation drugs. The durability of glycemic control also appears comparable to other newer agents. Sulfonylureas are the preferred treatment for some types of monogenic diabetes and selection of T2D patients who may have greater benefit from sulfonylureas based on certain phenotypes and genotypes is likely to be refined further by precision medicine. Sulfonylureas are inexpensive and readily available everywhere and they are still the most frequently used second-line treatment for T2D in many parts of the world.

Sulfonylureas in the Current Practice of Type 2 Diabetes Management: Are They All the Same? Consensus from the Gulf Cooperation Council (GCC) Countries Advisory Board on Sulfonylureas

Since their inception in the commercial market in the mid-twentieth century, sulfonylureas (SUs) have remained a therapeutic option in the management of type 2 diabetes (T2D). Despite their established glucose-lowering effects, there is no consensus among global experts and modern guidelines regarding the priority of SUs in relation to other therapeutic options, given the lack of evidence that SUs are associated with a low risk of macrovascular events and excess mortality. However, findings from recent trials and real-time observations have resolved this contentious issue somewhat, albeit to varying degrees. The present consensus discusses the role of SUs in contemporary diabetes management in the Gulf Cooperation Council (GCC) countries. Regional experts from these countries gathered virtually to formulate a consensus following presentations of topics relevant to SU therapy with an emphasis on gliclazide, including long-term efficacy, cost, end-organ benefits, and side effects, based on up-to-date evidence. The present narrative review reflects the conclusions of this assembly and provides a platform upon which future guidelines for the use of SUs in the GCC can be tailored.

The Impact of Low-dose Gliclazide on the Incretin Effect and Indices of Beta-cell Function

AIMS/HYPOTHESIS

Studies in permanent neonatal diabetes suggest that sulphonylureas lower blood glucose without causing hypoglycemia, in part by augmenting the incretin effect. This mechanism has not previously been attributed to sulphonylureas in patients with type 2 diabetes (T2DM). We therefore aimed to evaluate the impact of low-dose gliclazide on beta-cell function and incretin action in patients with T2DM.

METHODS

Paired oral glucose tolerance tests and isoglycemic infusions were performed to evaluate the difference in the classical incretin effect in the presence and absence of low-dose gliclazide in 16 subjects with T2DM (hemoglobin A1c < 64 mmol/mol, 8.0%) treated with diet or metformin monotherapy. Beta-cell function modeling was undertaken to describe the relationship between insulin secretion and glucose concentration.

RESULTS

A single dose of 20 mg gliclazide reduced mean glucose during the oral glucose tolerance test from 12.01 ± 0.56 to 10.82 ± 0.5mmol/l [P = 0.0006; mean ± standard error of the mean (SEM)]. The classical incretin effect was augmented by 20 mg gliclazide, from 35.5% (lower quartile 27.3, upper quartile 61.2) to 54.99% (34.8, 72.8; P = 0.049). Gliclazide increased beta-cell glucose sensitivity by 46% [control 22.61 ± 3.94, gliclazide 33.11 ± 7.83 (P = 0.01)] as well as late-phase incretin potentiation [control 0.92 ± 0.05, gliclazide 1.285 ± 0.14 (P = 0.038)].

CONCLUSIONS/INTERPRETATION

Low-dose gliclazide reduces plasma glucose in response to oral glucose load, with concomitant augmentation of the classical incretin effect. Beta-cell modeling shows that low plasma concentrations of gliclazide potentiate late-phase insulin secretion and increase glucose sensitivity by 50%. Further studies are merited to explore whether low-dose gliclazide, by enhancing incretin action, could effectively lower blood glucose without risk of hypoglycemia.

The Position of Gliclazide in the Evolving Landscapes and Disease Continuum of T2DM: A Collaborative Delphi Survey-Based Consensus from India

INTRODUCTION

This Delphi study aims to provide evidence-based expert opinion on the usage and current position of gliclazide in type 2 diabetes mellitus (T2DM) management in India.

METHODS

The single interaction modified Delphi-based methodology was used to collect opinions on gliclazide usage and its position in diabetes management from 338 endocrinologists/diabetologists who have had clinical experience with gliclazide. Participants, using a 9-point scale, were asked to rate eight statements comprising a total of 52 items on the related topics.

RESULTS

The Delphi consensus suggests that in drug-naïve patients with T2DM, intolerant to metformin or in whom metformin is contraindicated, dual therapy of gliclazide/gliclazide-modified release (MR) should be considered along with a dipeptidyl peptidase 4 (DPP4) inhibitor if glycated hemoglobin A1c level is greater than 7.5% and with insulin if the A1c level is greater than 9%. If the patients are inadequately controlled with metformin (A1c greater than 6.5% after 3 months of therapy), gliclazide/gliclazide-MR shall be added on to the treatment regimen to achieve greater and sustained reductions in A1c levels. However, it was not preferred over other antidiabetic classes in such clinical settings except alpha-glucosidase inhibitors (AGI). Early addition of gliclazide/gliclazide-MR shall be preferred over the up-titration of metformin beyond half-maximal dose for effective management of T2DM. Gliclazide/gliclazide-MR can be used safely in patients with diabetes and cardiovascular and chronic kidney disease. It can be used in older patients with T2DM as it does not have active metabolites and has a low risk of hypoglycemia.

CONCLUSION

The expert panel proposed consideration of monotherapy or dual therapy of gliclazide as an ideal choice in patients with T2DM because of its efficacy, long-term glycemic control, favorable renal outcomes, cardiovascular safety, and an optimal safety profile.

Glucagonotropic and Glucagonostatic Effects of KATP Channel Closure and Potassium Depolarization

The role of depolarization in the inverse glucose-dependence of glucagon secretion was investigated by comparing the effects of KATP channel block and of high potassium. The secretion of glucagon and insulin by perifused mouse islets was simultaneously measured. Lowering glucose raised glucagon secretion before it decreased insulin secretion, suggesting an alpha cell-intrinsic signal recognition. Raising glucose affected glucagon and insulin secretion at the same time. However, depolarization by tolbutamide, gliclazide, or 15 mM KCl increased insulin secretion before the glucagon secretion receded. In contrast to the robust depolarizing effect of arginine and KCl (15 and 40 mM) on single alpha cells, tolbutamide was of variable efficacy. Only when applied before other depolarizing agents had tolbutamide a consistent depolarizing effect and regularly increased the cytosolic Ca2+ concentration. When tested on inside-out patches tolbutamide was as effective on alpha cells as on beta cells. In the presence of 1 µM clonidine, to separate insulinotropic from glucagonotropic effects, both 500 µM tolbutamide and 30 µM gliclazide increased glucagon secretion significantly, but transiently. The additional presence of 15 or 40 mM KCl in contrast led to a marked and lasting increase of the glucagon secretion. The glucagon secretion by SUR1 knockout islets was not increased by tolbutamide, whereas 40 mM KCl was of unchanged efficiency. In conclusion a strong and sustained depolarization is compatible with a marked and lasting glucagon secretion. KATP channel closure in alpha cells is less readily achieved than in beta cells, which may explain the moderate and transient glucagonotropic effect.

Comparative effectiveness of gliclazide modified release versus sitagliptin as second-line treatment after metformin monotherapy in patients with uncontrolled type 2 diabetes

AIMS

To compare the effectiveness and safety of gliclazide modified release (MR) to sitagliptin as type 2 diabetes mellitus (T2D) treatments in a real-world patient population.

MATERIALS AND METHODS

This retrospective cohort study used records from the UK Clinical Practice Research Datalink. The cohort consisted of adult patients with T2D newly treated with either gliclazide MR or sitagliptin as second-line treatment added to metformin and with a glycated haemoglobin (HbA1c) level of ≥7.0% (53 mmol/mol). Patients were 1:1 matched using high-dimensional propensity score matching and followed to determine the time taken to reach an HbA1c <7.0%. Secondary outcomes included time to HbA1c ≤6.5% (48 mmol/mol), time to ≥1% (11 mmol/mol) HbA1c reduction from baseline, treatment persistence and durability, and hypoglycaemic events.

RESULTS

Among the 1986 patients included, those on gliclazide MR more likely achieved an HbA1c <7.0% [hazard ratio (HR): 1.35; 95% confidence interval (CI): 1.15-1.57], HbA1c ≤6.5% (HR: 1.51; 95% CI: 1.19-1.92) or had an HbA1c reduction ≥1% from baseline (HR: 1.11; 95% CI: 1.00-1.24) compared with patients on sitagliptin. Durability (log-rank P = .135) and persistence (P = .119) were similar between the two groups. Hypoglycaemic events were uncommon (23 total severe and non-severe events; incidence rate, 3.7 per 1000 patient years), with 4.7 and 2.6 events per 1000 patient years with gliclazide MR and sitagliptin treatment, respectively.

CONCLUSIONS

In this real-world study, second-line gliclazide MR was more effective than sitagliptin in reducing HbA1c, with similar durability and persistence and low rates of hypoglycaemic events, in individuals with T2D on metformin treatment and HbA1c above the target of 7.0%.

Reflections on the sulphonylurea story: A drug class at risk of extinction or a drug class worth reviving?

The role of sulphonylureas (SUs) in modern clinical practice poses ongoing clinical debate. With the advent of newer agents in diabetes management, there is an increasing shift away from the prescribing of SUs, but not necessarily to more effective agents. This review provides a different perspective on the debate, reflecting in depth upon the physiology of SUs, drawing on insights gained from monogenic diabetes to highlight the potential benefit of lower doses of SUs, and the probable benefit of gliclazide over most other, if not all SUs, in terms of sulphonylurea failure and cardiovascular outcomes.

Glimepiride Administered in Chow Reversibly Impairs Glucose Tolerance in Mice

Sulfonylureas are a class of antidiabetes medications prescribed to millions of individuals worldwide. Rodents have been used extensively to study sulfonylureas in the laboratory. Here, we report the results of studies treating mice with a sulfonylurea (glimepiride) in order to understand how the drug affects glucose homeostasis and tolerance. We tested the effect of glimepiride on fasting blood glucose, glucose tolerance, and insulin secretion, using glimepiride sourced from a local pharmacy. We also examined the effect on glucagon, gluconeogenesis, and insulin sensitivity. Unexpectedly, glimepiride exposure in mice was associated with fasting hyperglycemia, glucose intolerance, and decreased insulin. There was no change in circulating glucagon levels or gluconeogenesis. The effect was dose-dependent, took effect by two weeks, and was reversed within three weeks after removal. Glimepiride elicited the same effects in all strains evaluated: four wild-type strains, as well as the transgenic Grn-/- and diabetic db/db mice. Our findings suggest that the use of glimepiride as a hypoglycemic agent in mice should proceed with caution and may have broader implications about mouse models as a proxy to study the human pharmacopeia.

The place of gliclazide MR in the evolving type 2 diabetes landscape: A comparison with other sulfonylureas and newer oral antihyperglycemic agents

The sulfonylureas are effective oral glucose-lowering agents with a long history of clinical use. While all have the same general mechanism of action, their pharmacokinetic properties are influenced by factors such as dosage, rate of absorption, duration of action, route of elimination, tissue specificity, and binding affinity for pancreatic β-cell receptor. The result is a class of agents with similar HbA1c-lowering efficacy, but well-documented differences in terms of effects on hypoglycemia, and cardiovascular and renal safety. This review examines the differences between currently available sulfonylureas with a focus on how gliclazide modified release (MR) differs from other members of this class and from newer oral antihyperglycemic agents in the form of dipeptidyl peptidase-4 (DPP4) and sodium- glucose cotransporter 2 (SGLT2) inhibitors. The first part focuses on major outcome trials that have been conducted with the sulfonylureas and new oral agents. Consideration is then given to factors important for day-to-day prescribing including efficacy and durability, weight changes, hypoglycemia, renal effects and cost. Based on current evidence, third-generation sulfonylureas such as gliclazide MR possess many of the properties desired of a type 2 diabetes drug including high glucose-lowering efficacy, once-daily oral administration, few side effects other than mild hypoglycemia, and cardiovascular safety.

Canagliflozin, dapagliflozin and empagliflozin monotherapy for treating type 2 diabetes: systematic review and economic evaluation

BACKGROUND

Most people with type 2 diabetes are overweight, so initial treatment is aimed at reducing weight and increasing physical activity. Even modest weight loss can improve control of blood glucose. If drug treatment is necessary, the drug of first choice is metformin. However, some people cannot tolerate metformin, which causes diarrhoea in about 10%, and it cannot be used in people with renal impairment. This review appraises three of the newest class of drugs for monotherapy when metformin cannot be used, the sodium-glucose co-transporter 2 (SGLT2) inhibitors.

OBJECTIVE

To review the clinical effectiveness and cost-effectiveness of dapagliflozin (Farxiga, Bristol-Myers Squibb, Luton, UK), canagliflozin (Invokana, Janssen, High Wycombe, UK) and empagliflozin (Jardiance, Merck & Co., Darmstadt, Germany), in monotherapy in people who cannot take metformin.

SOURCES

MEDLINE (1946 to February 2015) and EMBASE (1974 to February 2015) for randomised controlled trials lasting 24 weeks or more. For adverse events, a wider range of studies was used. Three manufacturers provided submissions.

METHODS

Systematic review and economic evaluation. A network meta-analysis was carried out involving the three SGLT2 inhibitors and key comparators. Critical appraisal of submissions from three manufacturers.

RESULTS

We included three trials of dapagliflozin and two each for canagliflozin and empagliflozin. The trials were of good quality. The canagliflozin and dapagliflozin trials compared them with placebo, but the two empagliflozin trials included active comparators. All three drugs were shown to be effective in improving glycaemic control, promoting weight loss and lowering blood pressure (BP).

LIMITATIONS

There were no head-to-head trials of the different flozins, and no long-term data on cardiovascular outcomes in this group of patients. Most trials were against placebo. The trials were done in patient groups that were not always comparable, for example in baseline glycated haemoglobin or body mass index. Data on elderly patients were lacking.

CONCLUSIONS

Dapagliflozin, canagliflozin and empagliflozin are effective in improving glycaemic control, with added benefits of some reductions in BP and weight. Adverse effects are urinary and genital tract infections in a small proportion of users. In monotherapy, the three drugs do not appear cost-effective compared with gliclazide or pioglitazone, but may be competitive against sitagliptin (Januvia, Boehringer Ingelheim, Bracknell, UK).

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Predictors for the Treatment Effect of Sodium Glucose Co-transporter 2 Inhibitors in Patients with Type 2 Diabetes Mellitus

INTRODUCTION

Predictors for the effect of sodium glucose co-transporter 2 (SGLT2) inhibitors at lowering hemoglobin A1c (HbA1c) levels in type 2 diabetes mellitus patients remain unclear. We therefore aimed to elucidate these predictors in type 2 diabetes patients after 3 months of SGLT2 treatment.

METHODS

A total of 302 consecutive type 2 diabetes patients who had been treated with SGLT2 inhibitors as monotherapy or add-on therapy to existing antidiabetic treatments were enrolled retrospectively. After excluding 27 patients whose HbA1c levels could not be evaluated 3 months after treatment, the glucose-lowering effects of SGLT2 inhibitors were assessed in 275 patients by measuring HbA1c levels before and 3 months after treatment. The predictors for changes in HbA1c levels after 3 months of treatment were evaluated.

RESULTS

SGLT2 inhibitor treatment for 3 months decreased HbA1c levels from 7.8 ± 1.2% to 7.4 ± 1.0% (p < 0.0001). A multiple regression analysis showed that the independent determinants for SGLT2 inhibitor treatment effect included decreased HbA1c levels after 1 month of treatment, high baseline HbA1c levels, and a high estimated glomerular filtration rate (eGFR).

CONCLUSION

We show that type 2 diabetes patients who received the greatest glucose-lowering effect with SGLT2 inhibitor treatment were those with preserved renal function (high baseline eGFR) and high baseline HbA1c levels. Moreover, SGLT2 inhibitor treatment efficacy could be predicted by the patients' initial response to treatment.

Factors of primary and secondary sulfonylurea failure in type 2 diabetic subjects

BACKGROUND

The aim of the present study was to investigate the value of clinical characteristics in predicting sulfonylurea (SU) treatment responses.

METHODS

All 747 subjects in the present study were from the Xiaoke Pill Clinical Trial evaluating the safety and efficacy of SU. Subjects had the same initial dose of glibenclamide and drug doses were adjusted every 4 weeks during the 48-week follow-up period. Primary SU failure was defined as a <10% reduction in fasting plasma glucose (FPG) at the end of Week 4 from randomization, whereas secondary SU failure was defined as a consecutive confirmed level of FPG >7 mmol/L.

RESULTS

Kaplan-Meier survival analysis revealed that lower baseline basal disposition index (DI _b ) and higher FPG predict secondary SU failure. Inversely, higher baseline DI _b and lower FPG predict primary SU failure. Primary SU failure can predict secondary SU failure. The combination of lower baseline DI _b with primary SU failure is a better predictor of secondary SU failure than lower baseline DI _b or primary SU failure alone.

CONCLUSIONS

Patients with good glycemic control and higher β-cell reserve at entry are more likely to experience primary SU failure but are less likely to experience secondary SU failure. By combining baseline DI _b with initial response at the first month of treatment, we can get quick information about the long-term efficacy of SU treatment.

Is gliclazide a sulfonylurea with difference? A review in 2016

Sulfonylureas (SUs) remain the most commonly prescribed drug after metformin in the treatment of type 2 diabetes (T2DM), despite the availability of several newer agents. The primary reason of SUs being most popular is their quick glycemic response, time-tested experience and least cost. Although SUs are one amongst the several other second line agents after metformin in all major guidelines, the new Dutch type 2 guidelines specifically advise gliclazide as the preferred second line drug instead of SUs as a class. The World Health Organization (WHO) has also included gliclazide in their Model List of Essential Medicines 2013 motivated by its safety data in elderly patients. Specifically advising gliclazide may have been based on emerging evidence suggesting cardiovascular neutrality of gliclazide over other SUs. This prompted us to do a literature review of gliclazide efficacy and safety data compared to other SUs as well as oral anti-diabetic drugs.

Progression to insulin therapy among patients with type 2 diabetes treated with sitagliptin or sulphonylurea plus metformin dual therapy

AIM

To assess time to insulin initiation among patients with type 2 diabetes mellitus (T2DM) treated with sitagliptin versus sulphonylurea as add-on to metformin.

METHODS

This retrospective cohort study used GE Centricity electronic medical records and included patients aged ≥18 years with continuous medical records and an initial prescription of sitagliptin or sulphonylurea (index date) with metformin for ≥90 days during 2006-2013. Sitagliptin and sulphonylurea users were matched 1 : 1 using propensity score matching, and differences in insulin initiation were assessed using Kaplan-Meier curves and Cox regression. We used conditional logistic regression to examine the likelihood of insulin use 1-6 years after the index date for each year.

RESULTS

Propensity score matching produced 3864 matched pairs. Kaplan-Meier analysis showed that sitagliptin users had a lower risk of insulin initiation compared with sulphonylurea users (p = 0.003), with 26.6% of sitagliptin users initiating insulin versus 34.1% of sulphonylurea users over 6 years. This finding remained significant after adjusting for baseline characteristics (hazard ratio 0.76, 95% confidence interval 0.65-0.90). Conditional logistic regression analyses confirmed that sitagliptin users were less likely to initiate insulin compared with sulphonylurea users [odds ratios for years 1-6: 0.77, 0.79, 0.81, 0.57, 0.29 and 0.75, respectively (p < 0.05 for years 4 and 5)].

CONCLUSIONS

In this real-world matched cohort study, patients with T2DM treated with sitagliptin had a significantly lower risk of insulin initiation compared with patients treated with sulphonylurea, both as add-on to metformin.

Place of sulfonylureas in the management of type 2 diabetes mellitus in South Asia: A consensus statement

Since their introduction in clinical practice in the 1950's, Sulfonylureas (SUs) have remained the main-stay of pharmacotherapy in the management of type 2 diabetes. Despite their well-established benefits, their place in therapy is inappropriately being overshadowed by newer therapies. Many of the clinical issues associated with the use of SUs are agent-specific, and do not pertain to the class as such. Modern SUs (glimepiride, gliclazide MR) are backed by a large body of evidence, experience, and most importantly, outcome data, which supports their role in managing patients with diabetes. Person-centred care, i.e., careful choice of SU, appropriate dosage, timing of administration, and adequate patient counseling, will ensure that deserving patients are not deprived of the advantages of this well-established class of anti-diabetic agents. Considering their efficacy, safety, pleiotropic benefits, and low cost of therapy, SUs should be considered as recommended therapy for the treatment of diabetes in South Asia. This initiative by SAFES aims to encourage rational, safe and smart prescription of SUs, and includes appropriate medication counseling.

Predictive Factors for Efficacy of Dipeptidyl Peptidase-4 Inhibitors in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Predictive factors for the efficacy of dipeptidyl peptidase-4 (DPP-4) inhibitors for lowering glycosylated hemoglobin (HbA1c) remain unclear in patients with type 2 diabetes mellitus. The aim of this study is therefore to clarify predictive factors of the efficacy of DPP-4 inhibitors for lowering HbA1c after 12 months of treatment.

METHODS

A total of 191 consecutive type 2 diabetic patients (male sex 55%, mean age, 68.3±35.8 years), who had been treated with DPP-4 inhibitors for 12 months, were enrolled in this study and evaluated retrospectively.

RESULTS

After 12 months of DPP-4 inhibitor treatment, random blood glucose level, and HbA1c level, decreased from 167±63 to 151±49 mg/dL (P<0.01), and from 7.5%±1.3% to 6.9%±0.9% (P<0.01) respectively, without severe side effects. Multiple regression analysis showed that predictors of DPP-4 inhibitor treatment efficacy in lowering HbA1c level after 12 months were a decrease in HbA1c level after 3 months of treatment, a high baseline HbA1c level, a low baseline body mass index, and the absence of coronary artery disease.

CONCLUSION

Most suitable candidates for treatment with DPP-4 inhibitors are diabetics who are not obese and do not have coronary artery disease. In addition, long-term efficacy of DPP-4 inhibitors can be predicted by decrement of HbA1c after 3 months of treatment.

Paroxetine decreased plasma exposure of glyburide partly via inhibiting intestinal absorption in rats

Accumulating evidences have shown that diabetes is often accompanied with depression, thus it is possible that oral antidiabetic agent glyburide and antidepressive agent paroxetine are co-administered in diabetic patients. The aim of this study was to assess interactions between glyburide and paroxetine in rats. Effect of paroxetine on pharmacokinetics of orally administered glyburide was investigated. Effect of naringin (NAR), an inhibitor of rat intestinal organic anion transporting polypeptides 1a5 (Oatp1a5), on pharmacokinetics of glyburide was also studied. The results showed that co-administration of paroxetine markedly reduced plasma exposure and prolonged Tmax of glyburide, accompanied by significant increase in fecal excretion of glyburide. Co-administration of naringin also significantly decreased plasma exposure of glyburide. Data from intestinal perfusion experiments showed that both paroxetine and naringin significantly inhibited intestinal absorption of glyburide. Caco-2 cells were used to investigate whether paroxetine and naringin affected intestinal transport of glyburide and fexofenadine (a substrate of Oatp1a5). The results showed that both paroxetine and naringin greatly inhibited absorption of glyburide and fexofenadine. All results gave a conclusion that co-administration of paroxetine decreased plasma exposure of glyburide in rats via inhibiting intestinal absorption of glyburide, which may partly be attributed to the inhibition of intestinal Oatp1a5 activity.

Factors influencing the durability of the glucose-lowering effect of sitagliptin combined with a sulfonylurea

We analyzed the changes of glycemic control over 12 months and the factors influencing blood glucose in 162 Japanese patients with type 2 diabetes having inadequate glycemic control despite sulfonylurea-based therapy who received add-on sitagliptin. Hemoglobin A1c (HbA1c) decreased significantly after 4 weeks of treatment, and this improvement was maintained for 1 year, although HbA1c was slightly higher in week 52 than in week 24. Comparison of the patients showing a ≥0.4% increase of HbA1c between weeks 24 and 52 (n = 57) with the others (n = 105) showed a significant difference in the change of bodyweight, as well as the dose of glibenclamide (both P < 0.01). Although combined therapy with sitagliptin and a sulfonylurea seems to be effective for at least 1 year, blood glucose levels are more likely to increase again in patients who show greater weight gain after 24 weeks of treatment and those receiving a higher dose of glibenclamide.

Factors associated with reduced efficacy of sitagliptin therapy: analysis of 93 patients with type 2 diabetes treated for 1.5 years or longer

Background

Several studies have shown the effectiveness of sitagliptin, a dipeptidyl peptidase-4 inhibitor, for type 2 diabetes, with a hypoglycemic effect being demonstrated both when it is administered alone or in combination with other oral antidiabetic agents. However, there are few reports about its long-term efficacy, although medications for diabetes need to be effective over the long term. This study (as part of ASSET-K) aimed to investigate the efficacy and safety of sitagliptin when it was administered for 1.5 years or longer, and to explore factors associated with reduction of the therapeutic response.

Methods

Out of 375 patients treated with sitagliptin (50 mg/day) at Kanamori Diabetes Clinic between December 2009 and March 2012, 133 could be followed up for 72 weeks without interruption. After excluding 40 patients in whom the dosage and/or types of concomitant medications were modified during that period, the remaining 93 were included in this analysis. Clinical indices, such as blood glucose, HbA1c, and body weight, were investigated retrospectively. Compliance with diet and exercise therapy at 48 weeks was checked by a questionnaire.

Results

In the 93 patients analyzed (sitagliptin monotherapy, n = 9; combination therapy, n = 77; and switching from an alpha-glucosidase inhibitor or glinide, n = 7), hemoglobin A1c (HbA1c) showed a significant decrease after 24 weeks (7.70 ± 0.73% at baseline vs. 6.90 ± 0.55% at 24 weeks), but then showed a slight increase at 48 weeks. HbA1c was subsequently maintained in the same range with no significant changes until 72 weeks. A positive correlation was noted between the changes of HbA1c and body weight from 24 to 48 weeks. Compliance with diet and exercise therapy was worse in patients showing a ≥ 0.3% increase of HbA1c (n = 37) from 24 to 48 weeks than in the others (n = 56). Multiple logistic regression analysis showed that both factors were independent determinants of the increase of HbA1c from 24 weeks onward.

Conclusions

Sitagliptin showed good efficacy and safety when administered for 18 months as both monotherapy and combination therapy. Inadequate compliance with diet/exercise therapy and weight again may be associated with an increase of HbA1c over time during treatment with sitagliptin.

Initial sulfonylurea use and subsequent insulin therapy in older subjects with type 2 diabetes mellitus

BACKGROUND

In type 2 diabetes mellitus (T2DM), progressive loss of beta cell function over time requires treatment intensification and eventually initiation of insulin for many patients. Relative to metformin, a greater rate of decline in beta cell function over time has been observed with sulfonylurea treatment. The present study examined the association between initial monotherapy with metformin or sulfonylurea and subsequent initiation of insulin in older subjects with T2DM.

METHODS

In a retrospective cohort study using the GE electronic medical record database, eligible subjects with T2DM included those ≥65 years who received their first prescription of sulfonylurea or metformin as initial monotherapy between January 1, 2003 to December 31, 2008. The follow-up period lasted to the end of 2009 or the subject's latest data available. Insulin initiation was determined by prescription records. Logistic regression analysis evaluated the likelihood of insulin addition. A Cox regression model estimated time to initiation of insulin. Differences in baseline characteristics were controlled for using propensity score matching.

RESULTS

Overall, 12,036 subjects were included in the analysis. Mean age was 75 years and 50% were male. Subjects who initiated with sulfonylurea had a significantly (P < 0.001) higher incidence of insulin addition (2.8% vs. 1.4%) compared to those initiated with metformin within 1 year of follow-up. The likelihood of initiating insulin was higher in subjects initiated with sulfonylurea than with metformin (adjusted odds ratio 1.82, 95% confidence interval [CI] 1.40-2.38; P < 0.001). Sulfonylurea use was also significantly associated with a shorter time to insulin use compared to metformin (adjusted hazards ratio 2.10, 95% CI 1.83-2.39; P < 0.001).

CONCLUSION

In a cohort of older subjects with T2DM initiating antihyperglycemic therapy, new users of sulfonylurea monotherapy were more likely to receive insulin therapy and received it earlier than those starting with metformin.

Potentiation of sulfonylurea action by an EPAC-selective cAMP analog in INS-1 cells: comparison of tolbutamide and gliclazide and a potential role for EPAC activation of a 2-APB-sensitive Ca2+ influx

Tolbutamide and gliclazide block the K(ATP) channel K(ir)6.2/Sur1, causing membrane depolarization and stimulating insulin secretion in pancreatic beta cells. We examined the ability of the EPAC-selective cAMP analog 8-pCPT-2'-O-Me-cAMP-AM to potentiate the action of these drugs and the mechanism that might account for it. Insulin secretion stimulated by both 200 μM tolbutamide and 20 μM gliclazide, concentrations that had equivalent effects on membrane potential, was inhibited by thapsigargin (1 μM) or the L-type Ca(2+) channel blocker nicardipine (2 μM) and was potentiated by 8-pCPT-2'-O-Me-cAMP-AM at concentrations ≥2 μM in INS-1 cells. Ca(2+) transients stimulated by either tolbutamide or gliclazide were inhibited by thapsigargin or nicardipine and were significantly potentiated by 8-pCPT-2'-O-Me-cAMP-AM at 5 μM but not 1 μM. Both tolbutamide and gliclazide stimulated phospholipase C activity; however, only gliclazide did so independently of its activity at K(ATP) channels, and this activity was partially inhibited by pertussis toxin. 8-pCPT-2'-O-Me-cAMP-AM alone (5 μM) did not stimulate insulin secretion, but did increase intracellular Ca(2+) concentration significantly, and this activity was inhibited by 25 μM 2-aminoethoxydiphenylborate (2-APB) or the removal of extracellular Ca(2+). 8-pCPT-2'-O-Me-cAMP-AM potentiation of insulin secretion stimulated by tolbutamide was markedly inhibited by 2-APB (25 μM) and enhanced by the PKC inhibitor bisindolylmaleimide I (1 μM). Our data demonstrate that the actions of both tolbutamide and gliclazide are strongly potentiated by 8-pCPT-2'-O-Me-cAMP-AM, that gliclazide can stimulate phospholipase C activity via a partially pertussis toxin-sensitive mechanism, and that 8-pCPT-2'-O-Me-cAMP-AM potentiation of tolbutamide action may involve activation of a 2-APB-sensitive Ca(2+) influx.

Role of K(ATP) channels in β-cell resistance to oxidative stress

The importance of K(ATP) channels in stimulus-secretion coupling of β-cells is well established, although they are not indispensable for the maintenance of glycaemic control. This review article depicts a new role for K(ATP) channels by showing that genetic or pharmacological ablation of these channels protects β-cells against oxidative stress. Increased production of oxidants is a crucial factor in the pathogenesis of type 2 diabetes mellitus (T2DM). T2DM develops when β-cells can no longer compensate for the high demand of insulin resulting from excess fuel intake. Instead β-cells start to secrete less insulin and β-cell mass is diminished by apoptosis. Both, reduction of insulin secretion and β-cell mass induced by oxidative stress, are prevented by deletion or inhibition of K(ATP) channels. These findings may open up new insights into the early treatment of T2DM.

Transaminase levels in the upper normal range are associated with oral hypoglycemic drug therapy failure in patients with type 2 diabetes

Incident diabetes and the worsening of diabetes have recently been linked to hepatic steatosis. Aim of our study was to determine whether oral hypoglycemic agent failure is associated with higher transaminase levels (valid measure of liver steatosis). We selected 200 patients, attenders (3 consecutive annual evaluations) in our clinic, with type 2 diabetes among which 100 with oral hypoglycemic agents failure and 100 who were still responsive to oral therapy. Failure to therapy was defined as glycated hemoglobin >7.5% despite maximal-dose oral therapy. We analyzed patient histories and laboratory data. Compared with oral-therapy-responsive patients, those with failure had a significantly higher level mostly of alanine aminotransferase at the time of therapy failure and 2 years before. They were more likely to have had symptoms of hyperglycemia at the time of diabetes diagnosis. Regression analysis indicated that each 5-unit increase in transaminase levels independently increased the risk for oral hypoglycemic agents failure by 1.70. Higher liver transaminase levels, especially in patients who had symptomatic hyperglycemia at diabetes diagnosis, associate with oral hypoglycemic agent failure. The possible pathogenetic link between transaminase and declining islet function might consist of insulin resistance and increased circulating fatty acid levels, in turn causing liver steatosis and beta-cell dysfunction.

Improved glycemic control in pancreatic diabetes through intensive conservative insulin therapy

OBJECTIVE

The aim of this study was to evaluate the effectivity and safety of insulin therapy in patients with DM secondary to underlying chronic pancreatitis with initially inappropriate glycemic control.

METHODS

Pancreatic DM patients treated with oral antidiabetics (OAD) or pre-mixed insulin (PMI) with HbA1c ≥7.0% were recruited. Intensive conservative insulin treatment (ICT) (Group A, n = 16) or PMI (Group B, n = 8) was introduced instead of OAD, or the initial PMI therapy was switched to ICT (Group C, n = 10). The changes in HbA1c, fasting plasma glucose, body weight and hypoglycemic events from baseline to 2 years were followed.

RESULTS

The patients in Group A and B had been treated with oral antidiabetics for 55 ± 68 months before switching to insulin therapy. The level of HbA1c had worsened from 8.3 ± 1.5% to 9.8 ± 1.7% during this period. The ICT had reduced HbA1c significantly from 9.7 ± 1.8% to 7.6 ± 1.4% after 12 weeks, in Group A, and five patients had HbA1c<7.0%. The introduction of PMI in Group B reduced HbA1c from 10.0 ± 1.4% to 9.0 ± 0.6% by 12 weeks. None of the patients had HbA1c<7.0%. By 12 weeks, the introduction of ICT in Group C had reduced the level of HbA1c from 8.8 ± 1.7% to 7.7 ± 1.2%. Two patients reached HbA1c<7.0%. There were two severe hypoglycemic episodes during the 2 years, one-one case in Group A and B.

CONCLUSIONS

Oral medication becomes insufficient early in pancreatic DM. Long-term improvement of glycemic control can be achieved through intensified insulin therapy and in selected cases through PMI with a low risk of hypoglycemia.

Gliclazide may have an antiapoptotic effect related to its antioxidant properties in human normal and cancer cells

Experimental and clinical studies suggest that gliclazide may protect pancreatic β-cells from apoptosis induced by an oxidative stress. However, the precise mechanism(s) of this action are not fully understood and requires further clarification. Therefore, using human normal and cancer cells we examined whether the anti-apoptotic effects of this sulfonylurea is due to its free radical scavenger properties. Hydrogen peroxide (H₂O₂) as a model trigger of oxidative stress was used to induce cell death. Our experiments were performed on human normal cell line (human umbilical vein endothelial cell line, HUVEC-c) and human cancer cell lines (human mammary gland cell line, Hs578T; human pancreatic duct epithelioid carcinoma cell line, PANC-1). To assess the effect of gliclazide the cells were pre-treated with the drug. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay was employed to measure the impact of gliclazide on cell viability. Generation of reactive oxygen species, mitochondrial membrane potential (∆Ψ_m), and intracellular Ca²⁺ concentration [Ca²⁺] were monitored. Furthermore, the morphological changes associated with apoptosis were determined using double staining with Hoechst 33258-propidium iodide (PI). Gliclazide protects the tested cells from H₂O₂-induced cell death most likely throughout the inhibition of ROS production. Moreover, the drug restored loss of ΔΨ_m and diminished intracellular [Ca²⁺] evoked by H₂O₂. Double staining with Hoechst 33258-PI revealed that pre-treatment with gliclazide diminished the number of apoptotic cells. Our findings indicate that gliclazide may protect both normal and cancer human cells against apoptosis induced by H₂O₂. It appears that the anti-apoptotic effect of the drug is most likely associated with reduction of oxidative stress.

Probiotics decreased the bioavailability of the bile acid analog, monoketocholic acid, when coadministered with gliclazide, in healthy but not diabetic rats

In recent studies we showed that gliclazide has no hypoglycemic effect on type 1 diabetic (T1D) rats while MKC does, and their combination exerted a better hypoglycemic effect than MKC alone. We also showed that the most hypoglycemic effect was noticed when T1D rats were treated with probiotics then gavaged with MKC + gliclazide (blood glucose decreased from 24 ± 3 to 10 ± 2 mmol/l). The aim of this study is to investigate the influence of probiotics on MKC pharmacokinetics when coadministered with gliclazide, in T1D rats. 80 male Wistar rats (weight 350 ± 50 g) were randomly allocated into 8 groups (10 rats/group), 4 of which were injected with alloxan (30 mg/kg) to induce T1D. Group 1 was healthy and group 2 was diabetic. Groups 3 (healthy) and 4 (diabetic) were gavaged with probiotics (75 mg/kg) every 12 h for 3 days and 12 h later all groups received a single oral dose of MKC + gliclazide (4 and 20 mg/kg respectively). The remaining 4 groups were treated in the same way but administered MKC + gliclazide via the i.v. route. Blood samples collected from T1D rats prior to MKC + gliclazide revealed that probiotic treatment alone reduced blood glucose levels twofold. When coadministered with gliclazide, the bioavailability of MKC was reduced in healthy rats treated with probiotics but remained the same in diabetic pretreated rats. The decrease in MKC bioavailability, when administered with gliclazide, caused by probiotic treatment in healthy but not diabetic rats suggests that probiotic treatment induced MKC metabolism or impaired its absorption, only in healthy animals. The different MKC bioavailability in healthy and diabetic rats could be explained by different induction of presystemic elimination of MKC in the gut by probiotic treatment.

Differential effect of sulfonylureas on production of reactive oxygen species and apoptosis in cultured pancreatic beta-cell line, MIN6

Sulfonylureas are considered to cause beta-cell apoptosis. However, it is unclear how this occurs and whether there is a difference in such effects among various sulfonylureas. Here, we examined the effects of various sulfonylureas and a short-acting insulin secretagogue, nateglinide, on oxidative stress and apoptosis using the beta-cell line MIN6. After cultured MIN6 cells were exposed to various concentrations of sulfonylureas (glibenclamide, glimepiride, and gliclazide) or nateglinide, intracellular production of reactive oxygen species (ROS) was evaluated by staining with 2',7'-dichlorofluorescein diacetate. The effect of these agents on apoptosis was also evaluated by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling technique. Exposure of beta-cells to glibenclamide, glimepiride, and nateglinide significantly increased intracellular ROS production in a concentration-dependent manner (0.1-10 micromol/L). These effects were completely blocked by nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase inhibitors (diphenylene iodonium or apocynin) or a protein kinase C inhibitor (calphostin C). After exposure to these agents for 48 hours, the numbers of apoptotic cells were also significantly increased. These effects were significantly blocked by apocynin and antioxidant N-acetyl-L-cysteine. In contrast, exposure to any concentrations of gliclazide did not affect either intracellular ROS production or the numbers of apoptotic cells. Sulfonylureas (glibenclamide and glimepiride, but not gliclazide) and nateglinide stimulated ROS production via protein kinase C-dependent activation of NAD(P)H oxidase and consequently caused beta-cell apoptosis in vitro. Because of the lack of such adverse effects, gliclazide may have a benefit in the preservation of functional beta-cell mass.

Gliclazide protects human islet beta-cells from apoptosis induced by intermittent high glucose

BACKGROUND

Decreased beta-cell mass, mainly due to apoptosis, is crucial for the development and progression of type 2 diabetes. Chronic exposure to high glucose levels is a probable underlying mechanism, whereas the role of oral anti-diabetic agents (sulphonylureas in particular) is still unsettled.

METHODS

To directly investigate more on such issues, we prepared isolated human islets, which were then cultured for 5 days in continuous normal glucose concentration (NG, 5.5 mmol/L) or normal and high (HG, 16.7 mmol/L) glucose levels (alternating every 24 h), with or without the addition of therapeutical concentration (10 micromol L) of gliclazide or glibenclamide.

RESULTS

Intermittent high glucose caused a significant decrease of glucose-stimulated insulin secretion, which was not further affected by either sulphonylurea. Apoptosis, as assessed by electron microscopy, was also significantly increased by alternating high glucose exposure, which was accompanied by altered mitochondria morphology and density volume, and increased concentrations of nitrotyrosine, a marker of oxidative stress. Gliclazide, but not glibenclamide, was able to significantly reduce high glucose induced apoptosis, mitochondrial alterations, and nitrotyrosine concentration increase.

CONCLUSION

Therefore, gliclazide protected human beta-cells from apoptosis induced by intermittent high glucose, and this effect was likely to be due, at least in part, to the anti-oxidant properties of the molecule.

Overcoming the hurdles to achieving glycemic control

Several factors influence diabetes control, and many of these can adversely affect endeavors to obtain optimal glycemic management. For many patients with type 2 diabetes mellitus, the passage of time often results in a loss of responsiveness to medication and a greater difficulty in achieving desired target levels. Although these observations in part reflect a natural progression of diabetes, irrespective of treatment given, it is possible to identify modifiable hurdles that can be addressed with better outcome results. Lifestyle measures, particularly diet and exercise, remain paramount, whereas other secondary confounding factors such as systemic or endocrine disease or other conflicting medication need specific therapeutic attention. Most patients with type 2 diabetes mellitus will require oral hypoglycemic medication and this should be prescribed in the simplest, most effective, and safest way. Ensuring that patients fully understand treatment objectives is important resulting in better compliance with advised treatment. Such compliance can be significantly improved by keeping treatment regimens simple. With its novel once-daily formulation, gliclazide modified release has been shown to improve adherence to medication and result in better glycemic outcome as determined by improved HbA(1c) levels. Its benefits in terms of reduced risk of hypoglycemia have been demonstrated in the GlUcose control In type 2 diabetes: Diamicron modified release versus glimEpiride study.