Response to Chiasson et al.: Acarbose for the prevention of Type 2 diabetes, hypertension and cardiovascular disease in subjects with impaired glucose tolerance: facts and interpretations concerning the critical analysis of the STOP-NIDDM Trial data

Alpha-glucosidase inhibitors for prevention or delay of type 2 diabetes mellitus and its associated complications in people at increased risk of developing type 2 diabetes mellitus

BACKGROUND

Alpha-glucosidase inhibitors (AGI) reduce blood glucose levels and may thus prevent or delay type 2 diabetes mellitus (T2DM) and its associated complications in people at risk of developing of T2DM.

OBJECTIVES

To assess the effects of AGI in people with impaired glucose tolerance (IGT), impaired fasting blood glucose (IFG), moderately elevated glycosylated haemoglobin A1c (HbA1c) or any combination of these.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, and the reference lists of systematic reviews, articles and health technology assessment reports. The date of the last search of all databases was December 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), with a duration of one year or more, comparing AGI with any pharmacological glucose-lowering intervention, behaviour-changing intervention, placebo or no intervention in people with IFG, IGT, moderately elevated HbA1c or combinations of these.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

For this update of the Cochrane Review (first published 2006, Issue 4) we included 10 RCTs (11,814 participants), eight investigating acarbose and two investigating voglibose, that included people with IGT or people "at increased risk for diabetes". The trial duration ranged from one to six years. Most trials compared AGI with placebo (N = 4) or no intervention (N = 4).Acarbose reduced the incidence of T2DM compared to placebo: 670 out of 4014 people (16.7%) in the acarbose groups developed T2DM, compared to 812 out of 3994 people (20.3%) in the placebo groups (RR 0.82, 95% CI 0.75 to 0.89; P < 0.0001; 3 trials; 8008 participants; moderate-certainty evidence). One trial including participants with coronary heart disease and IGT contributed 64% of cases for this outcome. Acarbose reduced the risk of T2DM compared to no intervention: 7 out 75 people (9.3%) in the acarbose groups developed T2DM, compared to 18 out of 65 people (27.7%) in the no-intervention groups (RR 0.31, 95% CI 0.14 to 0.69; P = 0.004; 2 trials; 140 participants; very low-certainty evidence).Acarbose compared to placebo did not reduce or increase the risk of all-cause mortality (RR 0.98, 95% CI 0.82 to 1.18; P = 0.86; 3 trials; 8069 participants; very low-certainty evidence), cardiovascular mortality (RR 0.88; 95% CI 0.71 to 1.10; P = 0.26; 3 trials; 8069 participants; very low-certainty evidence), serious adverse events (RR 1.12, 95% CI 0.97 to 1.29; P = 0.13; 2 trials; 6625 participants; low-certainty evidence), non-fatal stroke (RR 0.50, 95% CI 0.09 to 2.74; P = 0.43; 1 trial; 1368 participants; very low-certainty evidence) or congestive heart failure (RR of 0.87; 95% CI 0.63 to 1.12; P = 0.40; 2 trials; 7890 participants; low-certainty evidence). Acarbose compared to placebo reduced non-fatal myocardial infarction: one out of 742 participants (0.1%) in the acarbose groups had a non-fatal myocardial infarction compared to 15 out of 744 participants (2%) in the placebo groups (RR 0.10, 95% CI 0.02 to 0.53; P = 0.007; 2 trials; 1486 participants; very low-certainty evidence). Acarbose treatment showed an increased risk of non-serious adverse events (mainly gastro-intestinal events), compared to placebo: 751 of 775 people (96.9%) in the acarbose groups experienced an event, compared to 723 of 775 people (93.3%) in the placebo groups (RR 1.04; 95% CI 1.01 to 1.06; P = 0.0008; 2 trials; 1550 participants). Acarbose compared to no intervention showed no advantage or disadvantage for any of these outcome measures (very low-certainty evidence).One trial each compared voglibose with placebo (1780 participants) or diet and exercise (870 participants). Voglibose compared to placebo reduced the incidence of T2DM: 50 out of 897 participants (5.6%) developed T2DM, compared to 106 out of 881 participants (12%) in the placebo group (RR 0.46, 95% CI 0.34 to 0.64; P < 0.0001; 1 trial; 1778 participants; low-certainty evidence). For all other reported outcome measures there were no clear differences between voglibose and comparator groups. One trial with 90 participants compared acarbose with diet and exercise and another trial with 98 participants reported data on acarbose versus metformin. There were no clear differences for any outcome measure between these two acarbose interventions and the associated comparator groups.None of the trials reported amputation of lower extremity, blindness or severe vision loss, end-stage renal disease, health-related quality of life, time to progression to T2DM, or socioeconomic effects.

AUTHORS' CONCLUSIONS

AGI may prevent or delay the development of T2DM in people with IGT. There is no firm evidence that AGI have a beneficial effect on cardiovascular mortality or cardiovascular events.

Effects of acarbose on cardiovascular and diabetes outcomes in patients with coronary heart disease and impaired glucose tolerance (ACE): a randomised, double-blind, placebo-controlled trial

BACKGROUND

The effect of the α-glucosidase inhibitor acarbose on cardiovascular outcomes in patients with coronary heart disease and impaired glucose tolerance is unknown. We aimed to assess whether acarbose could reduce the frequency of cardiovascular events in Chinese patients with established coronary heart disease and impaired glucose tolerance, and whether the incidence of type 2 diabetes could be reduced.

METHODS

The Acarbose Cardiovascular Evaluation (ACE) trial was a randomised, double-blind, placebo-controlled, phase 4 trial, with patients recruited from 176 hospital outpatient clinics in China. Chinese patients with coronary heart disease and impaired glucose tolerance were randomly assigned (1:1), in blocks by site, by a centralised computer system to receive oral acarbose (50 mg three times a day) or matched placebo, which was added to standardised cardiovascular secondary prevention therapy. All study staff and patients were masked to treatment group allocation. The primary outcome was a five-point composite of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, hospital admission for unstable angina, and hospital admission for heart failure, analysed in the intention-to-treat population (all participants randomly assigned to treatment who provided written informed consent). The secondary outcomes were a three-point composite outcome (cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke), death from any cause, cardiovascular death, fatal or non-fatal myocardial infarction, fatal or non-fatal stroke, hospital admission for unstable angina, hospital admission for heart failure, development of diabetes, and development of impaired renal function. The safety population comprised all patients who received at least one dose of study medication. This trial is registered with ClinicalTrials.gov, number NCT00829660, and the International Standard Randomised Controlled Trial Number registry, number ISRCTN91899513.

FINDINGS

Between March 20, 2009, and Oct 23, 2015, 6522 patients were randomly assigned and included in the intention-to-treat population, 3272 assigned to acarbose and 3250 to placebo. Patients were followed up for a median of 5·0 years (IQR 3·4-6·0) in both groups. The primary five-point composite outcome occurred in 470 (14%; 3·33 per 100 person-years) of 3272 acarbose group participants and in 479 (15%; 3·41 per 100 person-years) of 3250 placebo group participants (hazard ratio 0·98; 95% CI 0·86-1·11, p=0·73). No significant differences were seen between treatment groups for the secondary three-point composite outcome, death from any cause, cardiovascular death, fatal or non-fatal myocardial infarction, fatal or non-fatal stroke, hospital admission for unstable angina, hospital admission for heart failure, or impaired renal function. Diabetes developed less frequently in the acarbose group (436 [13%] of 3272; 3·17 per 100 person-years) compared with the placebo group (513 [16%] of 3250; 3·84 per 100 person-years; rate ratio 0·82, 95% CI 0·71-0·94, p=0·005). Gastrointestinal disorders were the most common adverse event associated with drug discontinuation or dose changes (215 [7%] of 3263 patients in the acarbose group vs 150 [5%] of 3241 in the placebo group [p=0·0007]; safety population). Numbers of non-cardiovascular deaths (71 [2%] of 3272 vs 56 [2%] of 3250, p=0·19) and cancer deaths (ten [<1%] of 3272 vs 12 [<1%] of 3250, p=0·08) did not differ between groups.

INTERPRETATION

In Chinese patients with coronary heart disease and impaired glucose tolerance, acarbose did not reduce the risk of major adverse cardiovascular events, but did reduce the incidence of diabetes.

FUNDING

Bayer AG.

Prediabetes: to treat or not to treat?

The incidence of diabetes is continuously increasing worldwide. Pre-diabetes (defined as impaired glucose tolerance, impaired fasting glucose or both) represents an intermediate state, which often progresses to overt diabetes within a few years. In addition, pre-diabetes may be associated with increased risk of microvascular and macrovascular complications. Thus, reverting a pre-diabetic state as well as preventing the development of diabetes represents enormous challenge for the clinician. Lifestyle modification in pre-diabetic individuals was found particularly effective in the prevention of diabetes. However, compliance to lifestyle modification measures can be a crucial problem in the everyday clinical practice, especially in developing countries. During the last decade many studies support the use of anti-diabetic treatment schemes in pre-diabetic subjects to be advantageous. The American Diabetes Prevention Program (DPP) as well as other minor studies and meta-analyses has convincingly demonstrated the efficacy of metformin in this patient group. In addition, results of the 10 year DPP follow up have recently been published, demonstrating the long term safety and sustainability of metformin treatment benefits in this population. In contrast to metformin, the evidence from the use of other anti-diabetic agents (thiazolidinediones, a-glucosidase inhibitors, incretin mimetics) in pre-diabetic individuals is rather inadequate and prospective data is further needed. Furthermore, large scale studies with hard clinical endpoints are needed to delineate the effect of pre-diabetes treatment on macro- and microvascular complications. In conclusion, several strategies of patient management, mainly lifestyle modification and pharmacological interventions can prevent diabetes development in subjects diagnosed with pre-diabetes or even revert pre-diabetic state. However, whether this biochemical improvement can be translated into actual clinical benefit remains to be established.

Blocking the renin-angiotensin-aldosterone system to prevent diabetes mellitus

Type 2 diabetes mellitus (DM) is increasing around the world, and the public health impact of DM, driven largely by cardiovascular disease complications, underpins the importance of continued efforts toward primary prevention of DM. Only a few interventions have been shown to prevent DM, with none of them yet proven to improve cardiovascular risk commensurately. Accumulating evidence suggest that drugs that block the renin-angiotensin-aldosterone system (RAAS), many of which have proven cardiovascular disease (CVD) benefit, also have favourable effects on parameters of glucose metabolism and incident diabetes. Here we review the evidence accumulated to date from animal studies, clinical mechanistic studies and clinical trials regarding the effect of RAAS inhibition and incident DM.

Is prevention of Type-2 diabetes feasible and efficient in primary care? A systematic PubMed review

AIM

To answer: (1) Do we have effective treatments to improve prognosis for those identified at risk of Type-2 diabetes? (2) Will prevention be cost-effective?

METHODS

A systematic search was done in PubMed using the following search strategy: "diabetes AND prevention AND (IFG OR IGT)". Restrictions were: "English, Meta-Analysis, Randomized Controlled Trial, Review, Humans".

RESULTS

Few randomised controlled preventive trials were found. Almost all were done in research settings in people with high risk of developing Type-2 diabetes. It seems possible to either delay or prevent Type-2 diabetes through lifestyle interventions and medication. Cost-utility analyses are few in number and come to very different conclusions as to whether health policy should promote prevention of Type-2 diabetes.

CONCLUSION

Intervention studies using lifestyle counselling and drug therapy in research settings illustrate promising results with lowering of the incidence of Type-2 diabetes, meaning that Type-2 diabetes can be delayed or prevented. It is, however, questionable whether these interventions are cost-effective. We need studies in routine clinical settings evaluating morbidity, mortality and cost-effectiveness as primary outcomes. While waiting for these studies to prove cost-effective, patients with pre-diabetes should be treated according to their 10-year risk of cardiovascular disease following present guidelines.

Alpha-glucosidase inhibitors for people with impaired glucose tolerance or impaired fasting blood glucose

BACKGROUND

Alpha-glucosidase inhibitors (AGIs) reduce blood glucose levels and may thus prevent type 2 diabetes and cardiovascular disease in patients with impaired glucose tolerance. These possible effects, and the effects on quality of life, plasma lipids and body weight, have never been investigated in a systematic literature review and meta-analysis.

OBJECTIVES

To assess the effects of alpha-glucosidase inhibitors in patients with impaired glucose tolerance (IGT) or impaired fasting blood glucose (IFBG), or both.

SEARCH STRATEGY

We searched The Cochrane Library (Clinical Trials database, formerly known as CENTRAL), PUBMED, EMBASE, Web of Science, LILACS, databases of ongoing trials, reference lists of relevant reviews, and we contacted experts and manufacturers. Date of last search was February 2006.

SELECTION CRITERIA

Randomised controlled trials of at least one-year duration in patients with IGT or IFBG, or both, comparing AGI monotherapy with any other intervention.

DATA COLLECTION AND ANALYSIS

Two reviewers read all abstracts, assessed quality and extracted data independently. Discrepancies were resolved by consensus or by the judgement of a third reviewer.

MAIN RESULTS

We included five trials (2360 participants), all investigating acarbose, that included patients with IGT or patients 'at increased risk for diabetes' (n = 1). Study duration was one, three (n = 2), five and six years. One study was at low risk of bias and four studies at high risk of bias. Except for the outcome incidence of type 2 diabetes in acarbose versus no treatment (two studies), meta-analyses were not possible. Data from the study at low risk of bias suggests that acarbose decreases the occurrence of type 2 diabetes (NNT = 10), cardiovascular events (NNT = 50, based on 47 events, study not initially powered for this outcome), post-load blood glucose (-0.6 mmol/L, 95% CI -1.0 to -0.3) and body mass index (0.3 kg/m(2), 95% CI -0.1 to -0.5). No statistically significant effects were observed on mortality, other morbidity, glycated haemoglobin, fasting blood glucose, lipids and blood pressure. The effects on the incidence of type 2 diabetes were confirmed in two studies at high risk of bias (OR 0.2, 95% CI 0.1 to 0.6). Adverse effects were mostly of gastro-intestinal origin (OR 3.5, 95% CI 2.7 to 4.4).

AUTHORS' CONCLUSIONS

There is evidence that acarbose reduces the incidence of type 2 diabetes in patients with IGT. However, it is unclear whether this should be seen as prevention, delay or masking of diabetes. Acarbose may prevent the occurrence of cardiovascular events, but this finding needs to be confirmed in more studies.

Can type 2 diabetes mellitus be considered preventable?

The primary prevention of type 2 diabetes mellitus (T2DM) is of great importance. There is now substantial evidence that T2DM can be prevented or delayed by lifestyle modification. A statistically significant reduction of relative risk of newly diagnosed T2DM was observed in large clinical trials with metformin, acarbose or orlistat in subjects with impaired glucose tolerance as well as with troglitazone in women with previous gestational diabetes. A relative risk reduction of newly diagnosed diabetes was observed in prospective, double blind clinical studies evaluating the effect of different antihypertensive drugs (ACE-inhibitors, angiotensin repector blockers, calcium channel blockers) or that of lipid-lowering agents (pravastatin) on the cardiovascular morbidity and mortality in high risk patients. In studies with postmenopausal hormone replacement therapy a relative risk reduction of newly developed T2DM was also observed. Thus, T2DM should be considered as a preventable disease. Nevertheless, it is noteworthy that oral antidiabetic drugs with an indication of preventing T2DM are not registered in several countries at present, so that drug therapy should not be used as a routine for preventing diabetes. On the other hand, patients with pre-diabetes (impaired fasting glycaemia, impaired glucose tolerance) should be given counseling on weight loss as well as instruction for increasing physical activity in order to prevent T2DM.