Combination therapy with sulfonylureas and metformin and the prevention of death in type 2 diabetes: a nested case-control study

Sulfonylureas as second line therapy for type 2 diabetes among veterans: Results from a National Longitudinal Cohort Study

AIMS

To assess if switching to or adding sulfonylureas increases major adverse cardiovascular events (MACE) or severe hypoglycemia versus remaining on metformin alone.

MATERIALS AND METHODS

This was a retrospective, longitudinal cohort utilizing United States Veterans Health Administration and Medicare data. Veterans with type 2 diabetes on metformin monotherapy between 2004 and 2006 were identified. Follow-up occurred through 2016. Those treated with either metformin plus a second-generation sulfonylurea (N = 45,305) or converted from metformin to a second-generation sulfonylurea (N = 2813) were compared to those receiving metformin monotherapy (N = 65,550). Hazard ratios (HR) and 95%CI from longitudinal competing risk Cox models were used to measure the association between sulfonylureas and outcomes.

RESULTS

Switching to or adding a sulfonylurea to metformin was associated with 3 times the risk of severe hypoglycemia versus metformin monotherapy (HR:3.44, 95% CI: 3.06,3.85 and HR: 3.08, 95% CI: 2.77,3.42, respectively). Switching to or adding a sulfonylurea to metformin was associated with a 7-19% higher risk of MACE versus metformin monotherapy (HR: 1.07, 95% CI: 1.00,1.14 and HR: 1.19, 95% CI: 1.13,1.25, respectively).

CONCLUSIONS

Switching to and adding second-generation sulfonylureas was associated an increase in severe hypoglycemia and MACE versus remaining on metformin alone. In an era where guidelines recommend diabetes therapies based on compelling indications, safety outcomes should be a key consideration when selecting therapy.

Sulphonylureas versus metformin and the risk of ventricular arrhythmias among people with type 2 diabetes: A population-based cohort study

AIM

To determine whether the use of sulphonylurea monotherapy, compared with metformin monotherapy, is associated with an increased risk of ventricular arrhythmia (VA) among patients initiating pharmacotherapy for type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted a population-based cohort study using electronic health data extracted from the UK's Clinical Practice Research Datalink Aurum. Using the active comparator, new-user cohort design, we compared rates of VA among patients aged 18 years or older using sulphonylurea monotherapy with those using metformin monotherapy as their initial pharmacological treatment for type 2 diabetes from April 1998 to December 2019. We used a Cox proportional hazards model with inverse probability of treatment weighting by propensity score to estimate the adjusted hazard ratio (aHR) and a corresponding bootstrap 95% confidence interval (CI) for VA with sulphonylurea monotherapy versus metformin monotherapy.

RESULTS

The cohort included 92 638 new users of sulphonylurea and 506 882 new users of metformin. A total of 279 VA events occurred among sulphonylurea users (rate per 10 000 person-years: 25.5, 95% CI: 22.7 to 28.7) and 1537 VA events occurred among metformin users (rate per 10 000 person-years: 18.5, 95% CI: 17.6 to 19.5). Compared with metformin, sulphonylureas were associated with an increased risk of VA (aHR: 1.42, 95% CI: 1.18 to 1.69).

CONCLUSIONS

Sulphonylureas are associated with an increased risk of VA when used as first-line therapy for type 2 diabetes relative to metformin use. This increased risk should be considered when prescribing sulphonylureas as an initial treatment for type 2 diabetes.

Sulfonylureas and the Risk of Ventricular Arrhythmias Among People with Type 2 Diabetes: A Systematic Review of Observational Studies

Previous studies have suggested an association between sulfonylureas and an increased risk of cardiovascular death among patients with type 2 diabetes. A potential mechanism involves sulfonylurea-induced ventricular arrhythmias (VAs). We conducted a systematic review of observational studies to determine whether the use of sulfonylureas, compared with the use of other antihyperglycemic drugs, is associated with the risk of VA (ventricular tachycardia, ventricular fibrillation, and premature ventricular complexes), cardiac arrest, and sudden cardiac death among patients with type 2 diabetes. Two independent reviewers searched MEDLINE, EMBASE, CINAHL Plus, CENTRAL, and ClinicalTrials.gov from inception to July 2021 for observational studies comparing sulfonylureas vs. other antihyperglycemic therapies or intraclass comparisons of sulfonylureas. Our systematic review included 17 studies (1,607,612 patients). Per Risk Of Bias In Non-randomized Studies of Interventions (ROBINS)-I, there were few high-quality studies (2 studies at moderate risk of bias; 4 at serious risk; and 11 at critical risk). All studies at a moderate or serious risk of bias reporting comparisons with other therapies were consistent with an increased risk of VA. Sulfonylureas were associated with a higher risk of arrhythmia vs. dipeptidyl peptidase-4 inhibitors (adjusted hazard ratio (aHR): 1.52, 95% confidence interval (CI): 1.27-1.80) and of VA vs. metformin (aHR: 1.52, 95% CI: 1.10-2.13). One moderate quality study reported inconsistent results for a composite of cardiac arrest/VA in analyses of US Medicaid claims and Optum claims data. Our systematic review suggests that, among higher-quality observational studies, sulfonylureas are associated with an increased risk of VA. However, we identified few methodologically rigorous studies, underscoring the need for additional real-world studies.

Clinical perspectives and concerns of metformin as an anti-aging drug

As percentages of elderly people rise in many societies, age-related diseases have become more prevalent than ever. Research interests have been shifting to delaying age-related diseases by delaying or reversing aging itself. We use metformin as an entry point to talk about the important molecular and genetic longevity-regulating mechanisms that have been extensively studied with it. Then we review a number of observational studies, animal studies, and clinical trials to reflect the clinical potentials of the mechanisms in lifespan extension, cardiovascular diseases, tumors, and neurodegeneration. Finally, we highlight remaining concerns that are related to metformin and future anti-aging research.

Mechanisms of action of metformin with special reference to cardiovascular protection

Management guidelines continue to identify metformin as initial pharmacologic antidiabetic therapy of choice for people with type 2 diabetes without contraindications, despite recent randomized trials that have demonstrated significant improvements in cardiovascular outcomes with newer classes of antidiabetic therapies. The purpose of this review is to summarize the current state of knowledge of metformin's therapeutic actions on blood glucose and cardiovascular clinical evidence and to consider the mechanisms that underlie them. The effects of metformin on glycaemia occur mainly in the liver, but metformin-stimulated glucose disposal by the gut has emerged as an increasingly import site of action of metformin. Additionally, metformin induces increased secretion of GLP-1 from intestinal L-cells. Clinical cardiovascular protection with metformin is supported by three randomized outcomes trials (in newly diagnosed and late stage insulin-treated type 2 diabetes patients) and a wealth of observational data. Initial evidence suggests that cotreatment with metformin may enhance the impact of newer incretin-based therapies on cardiovascular outcomes, an important observation as metformin can be combined with any other antidiabetic agent. Multiple potential mechanisms support the concept of cardiovascular protection with metformin beyond those provided by reduced blood glucose, including weight loss, improvements in haemostatic function, reduced inflammation, and oxidative stress, and inhibition of key steps in the process of atherosclerosis. Accordingly, metformin remains well placed to support improvements in cardiovascular outcomes, from diagnosis and throughout the course of type 2 diabetes, even in this new age of improved outcomes in type 2 diabetes.

Sulfonylureas as initial treatment for type 2 diabetes and the risk of adverse cardiovascular events: A population-based cohort study

AIMS

Sulfonylureas are recommended as second-line treatment in the management of type 2 diabetes. However, they are still commonly used also as first-line treatment instead of metformin. Given the controversial cardiovascular safety of sulfonylureas, we aimed to determine if their use as first-line treatment is associated with adverse cardiovascular events among patients with newly treated type 2 diabetes compared with metformin.

METHODS

We conducted a population-based cohort study of patients with newly treated type 2 diabetes using the UK's Clinical Practice Research Datalink. Initiators of metformin and sulfonylurea monotherapy were matched on high-dimensional propensity score, and Cox proportional hazards models were used to compare the rate of cardiovascular events (myocardial infarction, ischaemic stroke, cardiovascular death, and all-cause mortality) with sulfonylureas vs metformin.

RESULTS

Our cohort included 94 750 patients initiating treatment for type 2 diabetes, 17 612 on a sulfonylurea and 77 138 on metformin. After matching, sulfonylurea monotherapy, compared with metformin monotherapy, was not associated with an increased risk of myocardial infarction (hazard ratio [HR]: 1.04, 95% confidence interval [CI]: 0.85-1.25) but was associated with increased risks of ischaemic stroke (HR: 1.25, 95% CI: 1.002-1.56), cardiovascular death (HR: 1.25, 95% CI: 1.06-1.47), and all-cause mortality (HR: 1.60, 95% CI: 1.45-1.76). This represents an additional 2.0 ischaemic strokes, 3.5 cardiovascular deaths, and 21.4 all-cause deaths per 1,000 patients per year with sulfonylureas.

CONCLUSIONS

Initiating treatment of type 2 diabetes with a sulfonylurea rather than metformin is associated with higher rates of ischaemic stroke, cardiovascular death, and all-cause mortality.

Sulfonylureas as second line drugs in type 2 diabetes and the risk of cardiovascular and hypoglycaemic events: population based cohort study

OBJECTIVE

To assess whether adding or switching to sulfonylureas is associated with an increased risk of myocardial infarction, ischaemic stroke, cardiovascular death, all cause mortality, and severe hypoglycaemia, compared with remaining on metformin monotherapy in patients with type 2 diabetes.

DESIGN

Population based cohort study.

SETTING

General practices contributing data to the UK Clinical Practice Research Datalink.

PARTICIPANTS

Patients with type 2 diabetes initiating metformin monotherapy between 1998 and 2013.

MAIN OUTCOME MEASURES

Using the prevalent new-user cohort design we matched 1:1 patients adding or switching to sulfonylureas with those remaining on metformin monotherapy on high-dimensional propensity score, haemoglobin A1c, and number of previous metformin prescriptions. The two groups were compared using Cox proportional hazards models to estimate adjusted hazard ratios and 95% confidence intervals for the study outcomes.

RESULTS

Among 77 138 metformin initiators, 25 699 added or switched to sulfonylureas during the study period. During a mean follow-up of 1.1 years, sulfonylureas were associated with an increased risk of myocardial infarction (incidence rate 7.8 v 6.2 per 1000 person years, hazard ratio 1.26, 95% confidence interval 1.01 to 1.56), all cause mortality (27.3 v 21.5, 1.28, 1.15 to 1.44), and severe hypoglycaemia (5.5 v 0.7, 7.60, 4.64 to 12.44) compared with continuing metformin monotherapy. There was a trend towards increased risks of ischaemic stroke (6.7 v 5.5, 1.24, 0.99 to 1.56) and cardiovascular death (9.4 v 8.1, 1.18, 0.98 to 1.43). Compared with adding sulfonylureas, switching to sulfonylureas was associated with an increased risk of myocardial infarction (hazard ratio 1.51, 95% confidence interval, 1.03 to 2.24) and all-cause mortality (1.23, 1.00 to 1.50). No differences were observed for ischaemic stroke, cardiovascular death, or severe hypoglycaemia.

CONCLUSIONS

Sulfonylureas as second line drugs are associated with an increased risk of myocardial infarction, all cause mortality, and severe hypoglycaemia, compared with remaining on metformin monotherapy. Continuing metformin when introducing sulfonylureas appears to be safer than switching.

All-cause and cardiovascular mortality associated with sulphonylurea and metformin therapy in type 2 diabetes

PURPOSE

To test the hypothesis that cumulative exposure to sulphonylurea (SU) or metformin (MET) have different effects on mortality when taken as a replacement or add-on of one for the other.

METHODS

All consecutive diabetes patients aged over 20 years were screened at their first diabetes outpatient visit between 2001 and 2008 (n = 79869). Only patients on MET (n = 11374) or SU (n = 18502) monotherapy were retained. All patients were followed up for death until December 31, 2011, but censored at first exposure to anything else besides MET/SU. Adjusted time-dependent Cox regression and competing risk regression analysis, with daily updates of treatment modalities were performed.

RESULTS

Mean age was 62.1 ± 11.2 years and follow-up was 4.6 ± 3.2 years (138496 person-years). Adjusted all-cause and cardiovascular mortality rates were significantly higher in MET as compared with SU group. All-cause mortality hazard ratios (HR) for cumulative time exposure were as follows: HR 0.956 (95%CI 0.951-0.962, p < 0.001) for SU added to MET, HR 1.092 (95%CI 1.087-1.096, p < 0.001) for SU replacing MET, HR 0.979 (95%CI 0.975-0.983, p < 0.001) for MET added to SU, and HR 1.127 (95%CI 1.118-1.136, p < 0.001) for MET replacing SU.

CONCLUSION(S)

The effect on all-cause mortality was beneficial for MET+SU combined therapy, but deleterious for either SU replacing MET, or MET replacing SU. There were no major outcome differences when analyzing individual SU, or specific mortality.

Sulfonylureas and the Risks of Cardiovascular Events and Death: A Methodological Meta-Regression Analysis of the Observational Studies

Recent randomized trials have compared the newer antidiabetic agents to treatments involving sulfonylureas, drugs associated with increased cardiovascular risks and mortality in some observational studies with conflicting results. We reviewed the methodology of these observational studies by searching MEDLINE from inception to December 2015 for all studies of the association between sulfonylureas and cardiovascular events or mortality. Each study was appraised with respect to the comparator, the outcome, and study design-related sources of bias. A meta-regression analysis was used to evaluate heterogeneity. A total of 19 studies were identified, of which six had no major design-related biases. Sulfonylureas were associated with an increased risk of cardiovascular events and mortality in five of these studies (relative risks 1.16-1.55). Overall, the 19 studies resulted in 36 relative risks as some studies assessed multiple outcomes or comparators. Of the 36 analyses, metformin was the comparator in 27 (75%) and death was the outcome in 24 (67%). The relative risk was higher by 13% when the comparator was metformin, by 20% when death was the outcome, and by 7% when the studies had design-related biases. The lowest predicted relative risk was for studies with no major bias, comparator other than metformin, and cardiovascular outcome (1.06 [95% CI 0.92-1.23]), whereas the highest was for studies with bias, metformin comparator, and mortality outcome (1.53 [95% CI 1.43-1.65]). In summary, sulfonylureas were associated with an increased risk of cardiovascular events and mortality in the majority of studies with no major design-related biases. Among studies with important biases, the association varied significantly with respect to the comparator, the outcome, and the type of bias. With the introduction of new antidiabetic drugs, the use of appropriate design and analytical tools will provide their more accurate cardiovascular safety assessment in the real-world setting.

The Comparative Effectiveness of Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers in Patients With Diabetes

The evidence examining the effect of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) on mortality in high-risk patients is conflicting. To further examine this controversy, the authors compared outcomes between ACE inhibitors and ARBs in a large clinical diabetes registry. A retrospective cohort of 87,472 incident users followed for 105,702 patient-years was analyzed. Average age was 53.1±10.1 years, 54.2% were men, and 14.4% had cardiovascular disease. All-cause hospitalization or all-cause mortality, the composite primary endpoint, occurred in 10,943 (12.5%) patients. Compared with ACE inhibitors, the adjusted hazard for ARBs was 0.90 (95% confidence interval, 0.87-0.94) for all-cause hospitalization or mortality; 0.95 (0.65-1.40) for mortality; 0.90 (0.87-0.94) for all-cause hospitalization; and 0.81 (0.74-0.89) for cardiovascular admission. ARB use was associated with a reduced, not increased, risk of hospitalization/mortality relative to ACE inhibition. This was driven by lower hospitalization, with a null mortality result.

Can people with type 2 diabetes live longer than those without? A comparison of mortality in people initiated with metformin or sulphonylurea monotherapy and matched, non-diabetic controls

AIMS

Clinical and observational studies have shown an increased risk of cardiovascular events and death associated with sulphonylureas versus metformin. However, it has never been determined whether this was due to the beneficial effects of metformin or detrimental effects of sulphonylureas. The objective of this study was therefore to compare all-cause mortality in diabetic patients treated first-line with either sulphonylurea or metformin monotherapy with that in matched individuals without diabetes.

METHODS

We used retrospective observational data from the UK Clinical Practice Research Datalink (CPRD) from 2000. Subjects with type 2 diabetes who progressed to first-line treatment with metformin or sulphonylurea monotherapy were selected and matched to people without diabetes. Progression to all-cause mortality was compared using parametric survival models that included a range of relevant co-variables.

RESULTS

We identified 78,241 subjects treated with metformin, 12,222 treated with sulphonylurea, and 90,463 matched subjects without diabetes. This resulted in a total, censored follow-up period of 503,384 years. There were 7498 deaths in total, representing unadjusted mortality rates of 14.4 and 15.2, and 50.9 and 28.7 deaths per 1000 person-years for metformin monotherapy and their matched controls, and sulphonylurea monotherapy and their matched controls, respectively. With reference to observed survival in diabetic patients initiated with metformin monotherapy [survival time ratio (STR) = 1.0], adjusted median survival time was 15% lower (STR = 0.85, 95% CI 0.81-0.90) in matched individuals without diabetes and 38% lower (0.62, 0.58-0.66) in diabetic patients treated with sulphonylurea monotherapy.

CONCLUSIONS

Patients with type 2 diabetes initiated with metformin monotherapy had longer survival than did matched, non-diabetic controls. Those treated with sulphonylurea had markedly reduced survival compared with both matched controls and those receiving metformin monotherapy. This supports the position of metformin as first-line therapy and implies that metformin may confer benefit in non-diabetes. Sulphonylurea remains a concern.

Mortality risk with sulphonylureas compared to metformin

Current clinical guidelines in the USA and the UK recommend first-line glucose-lowering treatment with metformin monotherapy for glucose control in type 2 diabetes, where not contraindicated. Consequently, the proportion of people treated with sulphonylureas is decreasing. The purpose of this commentary is to discuss the risks and benefits associated with sulphonylurea monotherapy versus metformin monotherapy and the evidence that, in comparison with metformin, sulphonylureas cause increased harm to people with type 2 diabetes.

Establishing and managing a periodontal biobank for research: the sharing of experience

Periodontal bio-repositories, which allow banking of clinically validated human data and biological samples, provide an opportunity to derive biomarkers for periodontal diagnosis, prognosis and therapeutic activities which are expected to improve patient management. This article presents the establishing of the Malaysian Periodontal Database and Biobank System (MPDBS) which was initiated in 2011 with the aim to facilitate periodontal research. Partnerships were established with collaborating centres. Policies on specimen access, authorship and acknowledgement policies were agreed upon by all participating centres before the initiation of the periodontal biobank. Ethical approval for the collection of samples and data were obtained from institutional ethics review boards. A broad-based approach for informed consent was used, which covered areas related to quality of life impacts, genetics and molecular aspects of periodontal disease. Sample collection and processing was performed using a standardized protocol. Biobanking resources such as equipment and freezers were shared with the Malaysian Oral Cancer Database and Tissue Bank System (MOCDTBS). In the development of the MPDBS, challenges that were previously faced by the MOCDTBS were considered. Future challenges in terms of ethical and legal issues will be faced when international collaborations necessitate the transportation of specimens across borders.

[Cardiovascular effects and safety of glucose-lowering drugs: current situation]

Diabetes mellitus is an independent cardiovascular risk factor. Therefore, in addition to normalising blood glucose, the aim of the treatment for diabetes mellitus should be to prevent cardiovascular complications. However, the evidence available on the cardio-protective role of the different glucose-lowering drugs is scarce and poor, particularly as regards with the risk of major cardiovascular events. In this context, the regulatory agencies have modified the regulations for the approval of glucose-lowering drugs, now requiring to demonstrate the glucose-lowering effect together with a robust assessment of the cardiovascular safety. The aim of this work is to review the cardiovascular effects of the different glucose-lowering drugs, focusing on their impact on the risk of major cardiovascular events.

Cardiovascular risks and benefits with oral drugs for Type 2 diabetes mellitus

Type 2 diabetes mellitus affects approximately 321 million people worldwide. It is estimated that about half of these patients will die from cardiovascular complications. In spite of these statistics, medications for diabetes are approved based not on outcomes, but on surrogate markers such as blood glucose or glycosylated hemoglobin. In recent years, however, the safety of diabetes medications has come under scrutiny, and more studies are being undertaken to determine the effect(s) of the medications on actual outcomes. In this review the authors review available study results for all of the currently approved classes of oral medications for Type 2 diabetes, and discuss the possible mechanisms for the findings. More studies are necessary for many of these classes, however, to make definitive recommendations regarding their cardiovascular effects.

Mortality among veterans with type 2 diabetes initiating metformin, sulfonylurea or rosiglitazone monotherapy

AIMS/HYPOTHESES

Despite oral hypoglycaemic medications being the most commonly used pharmacological treatments for type 2 diabetes, research is limited on their comparative safety, particularly their effects on overall mortality. We compared mortality risk with monotherapy initiation of four oral hypoglycaemic medications in a nationwide cohort of US veterans with type 2 diabetes.

METHODS

We identified new users of oral hypoglycaemic medication monotherapy between 2004 and 2009 who received care for at least 1 year from the Veterans Health Administration.Patients were followed until initial monotherapy discontinuation,addition of another diabetes pharmacotherapy, death or end of follow-up. Mortality HRs were estimated using Cox regression adjusted for potential confounding factors.

RESULTS

Among new users of metformin, sulfonylureas and rosiglitazone (185,360 men, 7,812 women), 4,256 (2.2%) died during follow-up. Average duration of medication use ranged from 1.4 to 1.7 years. Significantly higher mortality risk was seen for glibenclamide (known as glyburide in the USA and Canada) (HR 1.38, 95% CI 1.27, 1.50) or glipizide (HR 1.55,95% CI 1.43, 1.67) compared with metformin monotherapy,and for glipizide compared with rosiglitazone (HR 1.27, 95%CI 1.01, 1.59) or glibenclamide monotherapy (HR 1.12, 95%CI 1.02, 1.23). A significant sex–rosiglitazone interaction was seen (p=0.034) compared with metformin monotherapy, with women having a higher HR (HR 4.36, 95% CI 1.34, 14.20)than men (HR 1.19, 95% CI 0.95, 1.49).

CONCLUSIONS/INTERPRETATIONS

Significantly higher mortality was associated with glibenclamide, glipizide and rosiglitazone use compared with metformin, and with glipizide use compared with rosiglitazone or glibenclamide. The potential for residual confounding by indication should be considered in interpreting these results.

Association of sulphonylurea treatment with all-cause and cardiovascular mortality: a systematic review and meta-analysis of observational studies

We conducted a meta-analysis of cohort and case-control studies to evaluate all-cause and cardiovascular (CV) mortality of patients with type 2 diabetes mellitus (T2DM) who received sulphonylurea (SU) treatment, when compared to any other diabetes treatment. Only studies reporting raw data on mortality during SU treatment were included. Data were combined using random-effects (RE) models. Unadjusted odds ratios (ORs) are presented. Of 4991 publication titles and abstracts reviewed, 20 studies (n = 551,912 patients) were included. For cohort studies (n = 276,050), patients receiving SU monotherapy or combination treatment had significantly higher all-cause and CV mortality risks compared to any non-SU treatment [all-cause, 13 studies: OR = 1.92, 95% confidence interval (CI) = 1.48-2.49; CV, 5 studies: OR = 2.72, 95% CI = 1.95-3.79]. Validity was limited by the high treatment group heterogeneity (I (2) > 90%) and study-inherent biases/design differences. In conclusion, patients receiving SU treatment had increased all-cause and CV mortality risks. However, the meta-analysis was limited by the high heterogeneity of non-randomized studies.

The Diabetes Pearl: Diabetes biobanking in The Netherlands

Background

Type 2 diabetes is associated with considerable comorbidity and severe complications, which reduce quality of life of the patients and require high levels of healthcare. The Diabetes Pearl is a large cohort of patients diagnosed with type 2 diabetes, covering different geographical areas in the Netherlands. The aim of the study is to create a research infrastructure that will allow the study of risk factors, including biomarkers and genetic determinants for severe diabetes complications.

Methods/design

Baseline examinations began November 2009 and will continue through 2012. By the end of 2012, it is expected that 7000 patients with type 2 diabetes will be included in the Diabetes Pearl cohort. To ensure quality of the data collected, standard operation procedures were developed and used in all 8 recruitment centers. From all patients who provide informed consent, the following information is collected: personal information, medication use, physical examination (antropometry, blood pressure, electrocardiography (ECG), retina photographs, ankle-brachial index, peripheral vibration perception), self-report questionnaire (socio-economic status, lifestyle, (family) history of disease, and psychosocial well-being), laboratory measurements (glucose, A1c, lipid profile, kidney function), biobank material (storage of urine and blood samples and isolated DNA). All gathered clinical data and biobank information is uploaded to a database for storage on a national level. Biobanks are maintained locally at all recruitment centers.

Discussion

The Diabetes Pearl is large-scale cohort of type 2 diabetes patients in the Netherlands aiming to study risk factors, including biomarkers and genetic markers, for disease deterioration and the development of severe diabetes complications. As a result of the well-designed research design and the national coverage, the Diabetes Pearl data can be of great value to national and international researchers with an interest in diabetes related research.

Reappraisal of metformin efficacy in the treatment of type 2 diabetes: a meta-analysis of randomised controlled trials

BACKGROUND

The UK Prospective Diabetes Study showed that metformin decreases mortality compared to diet alone in overweight patients with type 2 diabetes mellitus. Since then, it has been the first-line treatment in overweight patients with type 2 diabetes. However, metformin-sulphonylurea bitherapy may increase mortality.

METHODS AND FINDINGS

This meta-analysis of randomised controlled trials evaluated metformin efficacy (in studies of metformin versus diet alone, versus placebo, and versus no treatment; metformin as an add-on therapy; and metformin withdrawal) against cardiovascular morbidity or mortality in patients with type 2 diabetes. We searched Medline, Embase, and the Cochrane database. Primary end points were all-cause mortality and cardiovascular death. Secondary end points included all myocardial infarctions, all strokes, congestive heart failure, peripheral vascular disease, leg amputations, and microvascular complications. Thirteen randomised controlled trials (13,110 patients) were retrieved; 9,560 patients were given metformin, and 3,550 patients were given conventional treatment or placebo. Metformin did not significantly affect the primary outcomes all-cause mortality, risk ratio (RR)=0.99 (95% CI: 0.75 to 1.31), and cardiovascular mortality, RR=1.05 (95% CI: 0.67 to 1.64). The secondary outcomes were also unaffected by metformin treatment: all myocardial infarctions, RR=0.90 (95% CI: 0.74 to 1.09); all strokes, RR=0.76 (95% CI: 0.51 to 1.14); heart failure, RR=1.03 (95% CI: 0.67 to 1.59); peripheral vascular disease, RR=0.90 (95% CI: 0.46 to 1.78); leg amputations, RR=1.04 (95% CI: 0.44 to 2.44); and microvascular complications, RR=0.83 (95% CI: 0.59 to 1.17). For all-cause mortality and cardiovascular mortality, there was significant heterogeneity when including the UK Prospective Diabetes Study subgroups (I(2)=41% and 59%). There was significant interaction with sulphonylurea as a concomitant treatment for myocardial infarction (p=0.10 and 0.02, respectively).

CONCLUSIONS

Although metformin is considered the gold standard, its benefit/risk ratio remains uncertain. We cannot exclude a 25% reduction or a 31% increase in all-cause mortality. We cannot exclude a 33% reduction or a 64% increase in cardiovascular mortality. Further studies are needed to clarify this situation.

Variations in tissue selectivity amongst insulin secretagogues: a systematic review

AIM

Insulin secretagogues promote insulin release by binding to sulfonylurea receptors on pancreatic β-cells (SUR1). However, these drugs also bind to receptor isoforms on cardiac myocytes (SUR2A) and vascular smooth muscle (SUR2B). Binding to SUR2A/SUR2B may inhibit ischaemic preconditioning, an endogenous protective mechanism enabling cardiac tissue to survive periods of ischaemia. This study was designed to identify insulin secretagogues that selectively bind to SUR1 when given at therapeutic doses.

METHODS

Using accepted systematic review methods, three electronic databases were searched from inception to 13 June 2011. Original studies measuring the half-maximal inhibitory concentration (IC(50)) for an insulin secretagogue on K(ATP) channels using standard electrophysiological techniques were included. Steady-state concentrations (C(SS)) were estimated from the usual oral dose and clearance values for each drug.

RESULTS

Data were extracted from 27 studies meeting all inclusion criteria. IC(50) values for SUR1 were below those for SUR2A/SUR2B for all insulin secretagogues and addition of C(SS) values identified three distinct patterns. The C(SS) for gliclazide, glipizide, mitiglinide and nateglinide lie between IC(50) values for SUR1 and SUR2A/SUR2B, suggesting that these drugs bind selectively to pancreatic receptors. The C(SS) for glimepiride and glyburide (glibenclamide) was above IC(50) values for all three isoforms, suggesting these drugs are non-selective. Tolbutamide and repaglinide may have partial pancreatic receptor selectivity because IC(50) values for SUR1 and SUR2A/SUR2B overlapped somewhat, with the C(SS) in the midst of these values.

CONCLUSIONS

Insulin secretagogues display different tissue selectivity characteristics at therapeutic doses. This may translate into different levels of cardiovascular risk.