Meta-Analysis of Sulfonylurea Therapy on Long-Term Risk of Mortality and Cardiovascular Events Compared to Other Oral Glucose-Lowering Treatments

Incretin-based therapy and the risk of diabetic foot ulcers and related events

AIM

To investigate the effect of dipeptidyl peptidase-4 inhibitors (DPP4-Is) and glucagon-like peptide-1 receptor agonists (GLP1-RAs) on diabetic foot ulcer (DFU) and DFU-related outcomes (lower limb amputation [LLA], DFU-related hospitalization and mortality).

METHODS

We performed a cohort study with data from the Clinical Practice Research Datalink Aurum database with linkage to hospital data. We included people with type 2 diabetes starting treatment with metformin. Then we propensity score matched new users of DPP4-Is and sulphonylureas (N = 98 770), and new users of GLP1-RAs and insulin (N = 25 422). Cox proportional hazards models estimated the hazard ratios (HRs) for the outcomes.

RESULTS

We observed a lower risk of DFU with both DPP4-I use versus sulphonylurea use (HR 0.88, 95% confidence interval [CI]: 0.79-0.97) and GLP1-RA use versus insulin use (HR 0.44, 95% CI: 0.32-0.60) for short-term exposure (≤ 400 days) and HR 0.74 (95% CI: 0.60-0.92) for long-term exposure (>400 days). Furthermore, the risks of hospitalization and mortality were lower with both DPP4-I use and GLP1-RA use. The risk of LLA was lower with GLP1-RA use. The results remained consistent across several sensitivity analyses.

CONCLUSIONS

Incretin-based therapy was associated with a lower risk of DFU and DFU-related outcomes. This suggests benefits for the use of this treatment in people at risk of DFU.

Can metformin use reduce the risk of stroke in diabetic patients? A systematic review and meta-analysis

BACKGROUND AND AIM

Stroke and cardiovascular diseases are major causes of death and disability, especially among diabetic patients. Some studies have shown that metformin has been effective in preventing cardiovascular diseases. In this study, we aim to evaluate the effect of metformin on stroke in type 2 diabetic patients.

METHODS

A comprehensive search was conducted in Medline, Embase, Scopus, and Web of Science databases from their inception till 1st July 2022. Randomized clinical trials (RCT) and cohort studies were included. Two independent researchers screened the records, extracted the data, and assessed the risk of bias and certainty of evidence. Findings were reported as risk ratio (RR) and 95% confidence interval (CI). All statistical analyses were performed using the STATA 17.0 software package.

RESULTS

Analysis of 21 included studies with 1,392,809 patients demonstrated that metformin monotherapy was effective in reducing stroke risk in both RCTs (RR = 0.66, 95% CI: 0.50, 0.87 p = 0.004) and cohort studies (RR = 0.67, 95% CI: 0.55, 0.81, p < 0.0001). However, combined administration of metformin with other antihyperglycemic agents had no significant effect on stroke risk reduction in either the RCTs (RR = 0.92, 95% CI: 0.69, 1.22 p = 0.558) or the cohort studies (RR = 0.79, 95% CI: 0.59, 1.06, p = 0.122).

CONCLUSION

Low to moderate level of evidence in RCTs showed that metformin monotherapy could reduce stroke risk in type 2 diabetic patients. However, the preventive effect of metformin in stroke was not observed in patients who received a combination of metformin plus other hypoglycemic agents.

Glucocentric Drugs in Cardiovascular Disease Protection and Heart Failure

Evidence for cardiovascular outcomes with older-generation antihyperglycemic drugs in the management of type 2 diabetes is based on aggregated data from prior randomized controlled trials and observational studies that were not focused on prespecified cardiovascular end points. Newer antihyperglycemic medications have undergone a rigorous evaluation of cardiovascular outcomes through randomized controlled trials since the US Food and Drug Administration imposed a mandatory requirement for all glucose-lowering drugs in 2008. The three classes of drugs that have been most extensively studied are dipeptidyl peptidase 4 inhibitors, glucagon-like peptide 1 receptor agonists, and sodium-glucose cotransporter-2 (SGLT2) inhibitors, the latter two reporting significant reductions in adverse cardiovascular outcomes independent of their glycemic effect. Remarkably, it was the evidence from SGLT2 inhibitors cardiovascular outcome trials that prompted further evaluation of the drug class in patients with heart failure irrespective of their diabetes status, demonstrating a broader cardiometabolic effect of these drugs. In this review, we assess the evidence for cardiovascular outcomes with common older- and newer-generation glucose-lowering drugs in the management of type 2 diabetes. We also discuss emerging glucose-lowering drugs with novel metabolic targets that influence the risk of adverse cardiovascular events and expand on the role of these drugs beyond the management of type 2 diabetes.

Cardiovascular outcomes of type 2 diabetic patients treated with DPP‑4 inhibitors versus sulphonylureas as add-on to metformin in clinical practice

DPP-4 inhibitors (DPP-4i) and sulphonylureas remain the most widely prescribed add-on treatments after metformin. However, there is limited evidence from clinical practice comparing major adverse cardiovascular events (MACE) in patients prescribed these treatments, particularly among those without prior history of MACE and from vulnerable population groups. Using electronic health records from UK primary care, we undertook a retrospective cohort study with people diagnosed type-2 diabetes mellitus, comparing incidence of MACE (myocardial infarction, stroke, major cardiovascular surgery, unstable angina) and all-cause mortality among those prescribed DPP-4i versus sulphonylureas as add-on to metformin. We stratified analysis by history of MACE, age, social deprivation and comorbidities and adjusted for HbA1c, weight, smoking-status, comorbidities and medications. We identified 17,570 patients prescribed sulphonylureas and 6,267 prescribed DPP-4i between 2008-2017. Of these, 16.3% had pre-existing MACE. Primary incidence of MACE was similar in patients prescribed DPP-4i and sulphonylureas (10.3 vs 8.5 events per 1000 person-years; adjusted Hazard Ratio (adjHR): 0.94; 95%CI 0.80-1.14). For those with pre-existing MACE, rates for recurrence were higher overall, but similar between the two groups (21.8 vs 17.2 events per 1000 person-years; adjHR: 0.93; 95%CI 0.69-1.24). For those aged over 75 and with BMI less than 25 kg/m2 there was a protective effect for DPP-I, warranting further investigation. Patients initiating a DPP-4i had similar risk of cardiovascular outcomes to those initiating a sulphonylurea. This indicates the choice should be based on safety and cost, not cardiovascular prognosis, when deciding between a DPP-4i or sulphonylurea as add-on to metformin.

Use of DPP4i reduced odds of clinical deterioration and hyperinflammatory syndrome in COVID-19 patients with type 2 diabetes: Propensity score analysis of a territory-wide cohort in Hong Kong

BACKGROUND AND OBJECTIVES

Type 2 diabetes mellitus (T2DM) patients with Coronavirus Disease 2019 (COVID-19) have poorer prognosis. Inconclusive evidence suggested dipeptidyl peptidase-4 inhibitors (DPP4i) might reduce inflammation and prevent Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) entry, hence further evaluation on DPP4i is needed.

METHODS

1214 Patients with T2DM were admitted with COVID-19 between 21st January 2020 and 31st January 2021 in Hong Kong. Exposure was DPP4i use within the 90 days prior to admission for COVID-19. Assessed outcomes included clinical deterioration, clinical improvement, low viral load, positive Immunoglobulin G (IgG) antibody, hyperinflammatory syndrome, proportion of IgG antibody, clinical status and length of hospitalization. Multivariable logistic and linear regression models were performed to estimate odds ratios (OR) and their 95% confidence intervals (CI) of event outcomes and continuous outcomes, respectively.

RESULTS

DPP4i users (N = 107) was associated with lower odds of clinical deterioration (OR=0.71, 95%CI 0.54 to 0.93, P = 0.013), hyperinflammatory syndrome (OR=0.56, 95%CI 0.45 to 0.69, P < 0.001), invasive mechanical ventilation (OR=0.30, 95%CI 0.21 to 0.42, P < 0.001), reduced length of hospitalization (-4.82 days, 95%CI -6.80 to -2.84, P < 0.001), proportion of positive IgG antibody on day-3 (13% vs 8%, p = 0.007) and day-7 (41% vs 26%, P < 0.001), despite lack of association between DPP4i use and in-hospital mortality.

CONCLUSION

DPP4i use was associated with reduced odds of clinical deterioration and hyperinflammatory syndrome. Prospective studies are warranted to elucidate the role of DPP4i in T2DM and COVID-19.

Protocol for an observational cohort study investigating personalised medicine for intensification of treatment in people with type 2 diabetes mellitus: the PERMIT study

INTRODUCTION

For people with type 2 diabetes mellitus (T2DM) who require an antidiabetic drug as an add-on to metformin, there is controversy about whether newer drug classes such as dipeptidyl peptidase-4 inhibitors (DPP4i) or sodium-glucose co-transporter-2 inhibitors (SGLT2i) reduce the risk of long-term complications compared with sulfonylureas (SU). There is widespread variation across National Health Service Clinical Commissioning Groups (CCGs) in drug choice for second-line treatment in part because National Institute for Health and Care Excellence guidelines do not specify a single preferred drug class, either overall or within specific patient subgroups. This study will evaluate the relative effectiveness of the three most common second-line treatments in the UK (SU, DPP4i and SGLT2i as add-ons to metformin) and help target treatments according to individual risk profiles.

METHODS AND ANALYSIS

The study includes people with T2DM prescribed one of the second-line treatments-of-interest between 2014 and 2020 within the UK Clinical Practice Research Datalink linked with Hospital Episode Statistics and Office of National Statistics. We will use an instrumental variable (IV) method to estimate short-term and long-term relative effectiveness of second-line treatments according to individuals' risk profiles. This method minimises bias from unmeasured confounders by exploiting the natural variation in second-line prescribing across CCGs as an IV for the choice of prescribed treatment. The primary outcome to assess short-term effectiveness will be change in haemoglobin A1c (%) 12 months after treatment initiation. Outcome measures to assess longer-term effectiveness (maximum ~6 years) will include microvascular and macrovascular complications, all-cause mortality and hospital admissions during follow-up.

ETHICS AND DISSEMINATION

This study was approved by the Independent Scientific Advisory Committee (20-064) and the London School of Hygiene & Tropical Medicine Research Ethics Committee (21395). Results, codelists and other analysis code will be made available to patients, clinicians, policy-makers and researchers.

Weight change and risk of cardiovascular disease among adults with type 2 diabetes: more than 14 years of follow-up in the Tehran Lipid and Glucose Study

BACKGROUND

To examine the impact of weight change on incident cardiovascular disease and coronary heart disease (CVD/CHD) among an Iranian population with type 2 diabetes mellitus (T2DM).

METHODS

The study population included 763 participants with T2DM aged ≥ 30 years without a history of CVD and cancer at baseline. Two weight measurements done at baseline and about 3 years later. Based on their weight change, they categorized into: > 5% loss, 3-5% loss, stable (± < 3%), 3-5% gain, > 5% gain. Participants were then followed for incident CVD/CHD annually up to 20 March 2018. Multivariable Cox proportional hazard models, adjusted for age, sex, body mass index, educational level, current smoking, glucose-lowering drug use, family history of CVD, hypertension, hypercholesterolemia, chronic kidney disease, and fasting plasma glucose (FPG) were applied to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of weight change categories for incident CVD/CHD, considering stable weight as reference.

RESULTS

After the weight change measurement, during a median follow-up of 14.4 years, 258 CVD and 214 CHD occurred. Over 5% weight gain was associated with reduced risks of CVD and CHD development by the HRs of 0.70 [95% CI 0.48-1.01; P-value: 0.058] and 0.61 [0.40-0.93], respectively, in multivariable analysis. After further adjustment for FPG change, the HRs of weight gain > 5% were attenuated to 0.75 [0.51-1.10; P-value: 0.138] and 0.66 [043-1.01; P-value: 0.053] for incident CVD and CHD, respectively. The effect of weight loss > 5% was in opposite direction among those older versus younger than 60 years; with suggestive increased risk (not statistically significant) of incident CHD/CVD for the older group. Moreover, weight gain > 5% significantly reduced the risk of CHD only among those older than 60 years (P-value for interaction < 0.2). Furthermore, weight gain > 5% had an association with lower risk of CVD and CHD among sulfonylurea users (0.56 [0.32-0.98] for CVD and 0.54 [0.29-0.99] for CHD).

CONCLUSIONS

Our results with a long-term follow-up showed that weight gain > 5% was associated with better CVD/CHD outcomes among Iranian participants with T2DM, especially older ones. Moreover, we did not find an unfavorable impact on incident CVD/CHD for sulfonylurea-induced weight gain.

Cardiovascular events and mortality among type 2 diabetes mellitus patients newly prescribed first-line blood glucose-lowering drugs monotherapies: A population-based cohort study in the Catalan electronic medical record database, SIDIAP, 2010-2015

AIM

To assess cardiovascular (CV) events and all-cause mortality in type 2 diabetes mellitus (T2DM) patients treated with first-line monotherapies of non-insulin antidiabetic drugs (NIADs).

METHODS

Longitudinal retrospective cohort study in the Catalan database SIDIAP (Information System for the Development of Research in Primary Care). T2DM patients ≥18 years newly prescribed first-line monotherapies during 2010-2015 were followed since their first prescription until the composite of major adverse CV events, MACE (myocardium infarction [MI], stroke and all-cause death), its components, heart failure (HF) and peripheral artery disease (PAD) or censoring. Cox proportional hazard models were used to estimate hazard ratios 95% confidence interval (HR [95%CI]).

RESULTS

Compared with metformin, the use of sulfonylureas, dipeptidyl peptidase-4 inhibitors (DPP-4 i) and meglitinides were significantly associated with higher risk for MACE (1.55 [1.42-1.68]); 1.49 [1.22-1.84] and 2.01 [1.29-3.12]) and all-cause mortality (1.67 [1.52-1.84], 1.65 [1.30-2.] and 2.08 [1.26-3.42]). Sulfonylureas users had increased risk of MI (1.38 [1.03-1.85]) stroke (1.31 [1.11-1.54]), HF (1.49 [1.28-1.72]) and PAD (1.24 [1.02-1.51]). Meglitinides users were at increased risks of MI, HR 2.03 (1.10-3.74).

CONCLUSION

In first-line monotherapies, compared with metformin, sulfonylureas were associated with increased risks in all the outcomes; DPP-4 i and repaglinide showed increased risks of MACE and mortality. Residual confounding cannot be ruled out.

The present and future scope of real-world evidence research in diabetes: What questions can and cannot be answered and what might be possible in the future?

The last decade has witnessed an exponential growth in the opportunities to collect and link health-related data from multiple resources, including primary care, administrative, and device data. The availability of these "real-world," "big data" has fuelled also an intense methodological research into methods to handle them and extract actionable information. In medicine, the evidence generated from "real-world data" (RWD), which are not purposely collected to answer biomedical questions, is commonly termed "real-world evidence" (RWE). In this review, we focus on RWD and RWE in the area of diabetes research, highlighting their contributions in the last decade; and give some suggestions for future RWE diabetes research, by applying well-established and less-known tools to direct RWE diabetes research towards better personalized approaches to diabetes care. We underline the essential aspects to consider when using RWD and the key features limiting the translational potential of RWD in generating high-quality and applicable RWE. Only if viewed in the context of other study designs and statistical methods, with its pros and cons carefully considered, RWE will exploit its full potential as a complementary or even, in some cases, substitutive source of evidence compared to the expensive evidence obtained from randomized controlled trials.

Neuromodulatory effects of anti-diabetes medications: A mechanistic review

Diabetes mellitus is a potent upstream event in the molecular pathophysiology which gives rise to various diabetes-related complications. There are several classes of anti-diabetic medications that have been developed to normalize blood glucose concentrations through a variety of molecular mechanisms. Beyond glucose-lowering effects, these agents may also provide further therapeutic potential. For instance, there is a high incidence of diabetes-induced neuronal disorders among patients with diabetes, who may also develop neurodegenerative and psychological complications. If anti-diabetic agents can modify the molecular mechanisms involved in the pathophysiology of neuronal comorbidities, this could potentially be translated to reducing the risk of other neurological conditions such as Alzheimer's disease, Parkinson's disease, depression, memory deficits and cognition impairments among patients with diabetes. This review aimed to shed light on some of the potentially beneficial aspects of anti-diabetic agents in lowering the risk or treating neuronal disorders by reviewing the molecular mechanisms by which these agents can potentially modulate neuronal behaviors.

The Effects of SGLT2 Inhibitors on Cardiovascular and Renal Outcomes in Diabetic Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Previous meta-analyses demonstrated the benefits of sodium-glucose cotransporter 2 inhibitors (SGLT2i) primarily on patients with established atherosclerotic cardiovascular disease (ASCVD), but with questionable efficacy on patients at risk of ASCVD. Additionally, evidence of beneficial cardiorenal outcomes in patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 with the CV outcomes trials remains unclear. Canagliflozin, one of the SGLT2i, has recently been studied in a large randomized controlled trial in diabetic patients with chronic kidney disease. Thus, there is a need to understand the combined outcomes on the population targeted for treatment with SGLT2i as a whole, regardless of ASCVD status. This meta-analysis will therefore assess the efficacy of SGLT2i in cardiovascular and renal outcomes in general, and in patients with eGFR under 60 mL/min/1.73 m2 in particular.

METHODS

We searched PubMed and Cochrane databases for randomized, placebo-controlled studies involving SGLT2i. We examined composite cardiovascular outcomes of death from cardiovascular causes, nonfatal myocardial infarctions, nonfatal stroke, and heart failure hospitalizations. Renal composite outcomes and progression of albuminuria were also analyzed. Pooled relative risks (RR) and their 95% confidence intervals (CI) were calculated using a fixed-effects model.

RESULTS

The search yielded a total of 252 articles. Four studies were ultimately included in the meta-analysis after exclusion of other irrelevant studies. The pooled RR (95% CI) for the composite cardiovascular outcome was 0.93 (0.87-0.99) with a number needed to treat (NNT) of 167 in the general study population and 0.89 (0.77-1.02) in patients with eGFR <60 mL/min/1.73 m2. The pooled RR for all-cause mortality was 0.9 (0.84-0.97) with NNT = 143. The pooled RR for death from cardiovascular causes alone was 0.89 (0.81-0.99) in the general population and 0.82 (0.62-1.07) in patients with eGFR <60 mL/min/1.73 m2. The pooled RR for heart failure hospitalizations was 0.71 (0.63-0.79) with NNT = 91. With respect to renal outcomes, the pooled RR for the composite renal outcome was 0.63 (0.56-0.71) with NNT = 67; this was true even in patients with eGFR <60 mL/min/1.73 m2 0.67 (0.59-0.76). Lastly, the pooled RR for progression of albuminuria was 0.80 (0.76-0.84).

CONCLUSION

SGLT2i are associated with significantly lower major adverse cardiovascular events, heart failure hospitalizations, and all-cause mortality. The evidence is strongest in reducing heart failure hospitalizations. However, the evidence is weaker when it comes to the population subset with eGFR <60 mL/min/1.73 m2. SGLT2i are also associated with significantly lower adverse renal events, with these effects apparent even in the population with eGFR <60 mL/min/1.73 m2.

Long-term comparative safety analysis of the risks associated with adding or switching to a sulfonylurea as second-line Type 2 diabetes mellitus treatment in a US veteran population

AIM

To examine the risks of all-cause mortality and cardiovascular events associated with adding vs switching to second-line therapies in a comparative safety study of people with Type 2 diabetes mellitus.

METHODS

We conducted a retrospective cohort study using an as-treated analysis of people served by the Veterans Health Administration who were on metformin and subsequently augmented this treatment or switched to other oral glucose-lowering treatments between 1998 and 2012. This study included 145 250 people with long follow-up. Confounding was addressed through several strategies, involving weighted propensity score models with rich confounder adjustment and strict inclusion criteria, coupled with an incident-user design.

RESULTS

Second-line use of sulfonylureas was related to higher mortality (hazard ratio 1.39, 95% CI 1.14, 1.70) and cardiovascular risks (hazard ratio 1.19, 95% CI 1.09, 1.30) compared with thiazolidinedione therapy. Differential hazards were associated with discontinuing or not discontinuing metformin; switching to sulfonylurea therapy was associated with a higher risk of all-cause mortality and cardiovascular events compared with all other therapies. Furthermore, add-on sulfonylurea therapy was associated with an elevated risk for both outcomes when compared with thiazolidinedione add-on therapy.

CONCLUSIONS

The results of the present study may inform decisions on whether to augment or discontinue metformin; when considering the long-term risks, switching to a sulfonylurea appears unfavourable compared with other therapies. Instead, adding a thiazolidinedione to existing metformin therapy appears to be superior to adding or switching to a sulfonylurea.

Managing Cardiovascular Risk in Type 2 Diabetes: What Do the Cardiovascular Outcome Trials Mean for Australian Practice?

Understanding the implications of cardiovascular (CV) outcomes data of glucose-lowering agents on the management of type 2 diabetes mellitus can be challenging for many primary practitioners. Amongst different classes of diabetes medications assessed for CV safety, several agents within the sodium-glucose transport protein-2 inhibitor and glucagon-like peptide-1 receptor agonists classes have demonstrated CV risk reduction. Applying the trial findings to patients typically seen in clinical practice, such as those with established CV disease and those with multiple CV risk factors without established CV disease, requires further clarity. To bridge this gap in our current knowledge, the aim of this review was to utilise expert-driven opinions on common case scenarios and practical recommendations on the most appropriate choice of agents, according to an individual patient's clinical risk profile (CV and kidney disease), treatment preference and reimbursement environment from an Australian perspective.Funding: Boehringer Ingelheim Australia.

Class effects of SGLT2 inhibitors on cardiorenal outcomes

BACKGROUND

To summarize the four recent sodium-glucose cotransporter 2 inhibitor (SGLT2i) trials: Dapagliflozin Effect on CardiovascuLAR Events (DECLARE-TIMI 58), CANagliflozin CardioVascular Assessment Study (CANVAS) Program, Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME), Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation (CREDENCE), and explore the potential determinants for their cardiovascular, renal, and safety outcomes.

RESULTS

The composite renal outcome event rates per 1000 patient-years for drug and placebo, as well as the corresponding relative risk reductions, were 3.7, 7.0, 47%; 5.5, 9.0, 40%; 6.3, 11.5, 46%; 43.2, 61.2, 30% for DECLARE-TIMI 58, CANVAS, EMPA-REG OUTCOME, and CREDENCE, respectively (event definitions varied across trials). The major adverse cardiovascular (CV) event rates per 1000 patient-years for drug and placebo, as well as the corresponding relative risk reductions, were 22.6, 24.2, 7%; 26.9, 31.5, 14%; 37.4, 43.9, 14%; 38.7, 48.7, 20% for DECLARE-TIMI 58, CANVAS, EMPA-REG OUTCOME, and CREDENCE, respectively. DECLARE-TIMI 58 had the fewest cardiorenal events and CREDENCE the most. These differences were presumably due to varying inclusion criteria resulting in DECLARE-TIMI 58 having the best baseline renal filtration function and CREDENCE the worst (mean estimated glomerular filtration rate 85.2, 76.5, 74, 56.2 mL/min/1.73 m2 for DECLARE-TIMI 58, CANVAS, EMPA-REG OUTCOME, and CREDENCE, respectively). Additionally, CREDENCE had considerably higher rates of albuminuria (median urinary albumin-creatinine ratios (UACR) were 927, 12.3, and 13.1 mg/g for CREDENCE, CANVAS, and DECLARE-TIMI 58, respectively; EMPA-REG OUTCOME had 59.4% UACR < 30, 28.6% UACR > 30-300, 11.0% UACR > 300 mg/g).

CONCLUSIONS

Dapagliflozin, empagliflozin, and canagliflozin have internally and externally consistent and biologically plausible class effects on cardiorenal outcomes. Baseline renal filtration function and degree of albuminuria are the most significant indicators of risk for both CV and renal events. Thus, these two factors also anticipate the greatest clinical benefit for SGLT2i.

Hypoglycaemic effects of glimepiride in sulfonylurea receptor 1 deficient rat

BACKGROUND AND PURPOSE

Sulfonylureas (SUs) have been suggested to have an insulin-independent blood glucose-decreasing activity due to an extrapancreatic effect. However, a lack of adequate in vivo evidence makes this statement controversial. Here, we aimed to evaluate whether glimepiride has extrapancreatic blood glucose-lowering activity in vivo.

EXPERIMENTAL APPROACH

Sulfonylurea receptor 1 deficient (SUR1^-/- ) rats were created by means of transcription activator-like effector nucleases (TALEN)-mediated gene targeting technology. Type 2 diabetic models were established by feeding a high-fat diet and administering a low-dose of streptozotocin. These rats were then randomly divided into four groups: glimepiride, gliclazide, metformin and saline. All rats were treated for 2 weeks.

KEY RESULTS

Glimepiride decreased blood glucose levels and increased insulin sensitivity without elevating insulin levels. Gliclazide showed similar effects as glimepiride. Both agents were weaker than metformin. Further mechanistic investigations revealed that glimepiride increased hepatic glycogen synthesis and decreased gluconeogenesis, which were accompanied by the activation of Akt in the liver. Moreover, glimepiride increased both total and membrane glucose transporter 4 (GLUT4) levels in muscle and fat, which might be attributed to insulin receptor-independent IRS1/Akt activation.

CONCLUSION AND IMPLICATIONS

Glimepiride possesses an extrapancreatic blood glucose-lowering effect in vivo, which might be attributed to its direct effect on insulin-sensitive tissues. Therefore, the combination of glimepiride with multiple insulin injections should not be excluded per se.