Metformin versus insulin in gestational diabetes mellitus: a meta-analysis of randomized clinical trials

Effectiveness of antidiabetic agents for treatment of gestational diabetes: A methodological quality assessment of meta-analyses and network meta-analysis

AIMS/INTRODUCTION

Despite there being several meta-analyses on the effects of antidiabetic agents in patients with gestational diabetes mellitus, the reliability of their findings is a concern, mainly due to undetermined methodological quality of these studies. This study aimed to assess the methodological quality of available meta-analyses and provide a summary estimation of the effectiveness of treatments modalities.

MATERIALS AND METHODS

PubMed, Web of Science and Scopus databases were comprehensively searched for retrieving relevant meta-analyses published in English up to May 2020. A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) was applied to evaluate methodological quality of eligible meta-analyses. A network meta-analysis was used to calculate the pooled odds ratio of maternal and neonatal outcomes in gestational diabetes mellitus patients treated with metformin or glyburide compared with those treated with insulin. The rank network analysis was carried out for ranking of the treatments and reporting the most efficient treatment.

RESULTS

A total of 27 and 17 studies were included for qualitative and quantitative syntheses, respectively; of these, just four studies were classified as high quality. The results showed that metformin had the highest probability of being the best treatment, compared with insulin and glyburide, for the majority of adverse neonatal outcomes, whereas glyburide was the best treatment in reducing the risk of adverse maternal outcomes. The results were not significantly changed after excluding low-quality studies.

CONCLUSIONS

This review study of available literature shows that metformin can be a superior option in most neonatal and maternal adverse pregnancy outcomes in women with gestational diabetes mellitus; the results need to be further updated by including future more qualified studies.

Prevention of Hypertensive Disorders of Pregnancy-Is There a Place for Metformin?

The possibility of prophylaxis of hypertensive disorders of pregnancy (HDPs) such as preeclampsia (PE) and pregnancy-induced hypertension is of interest due to the unpredictable course of these diseases and the risks they carry for both mother and fetus. It has been proven that their development is associated with the presence of the placenta, and the processes that initiate it begin at the time of the abnormal invasion of the trophoblast in early pregnancy. The ideal HDP prophylaxis should alleviate the influence of risk factors and, at the same time, promote physiological trophoblast invasion and maintain the physiologic endothelium function without any harm to both mother and fetus. So far, aspirin is the only effective and recommended pharmacological agent for the prevention of HDPs in high-risk groups. Metformin is a hypoglycemic drug with a proven protective effect on the cardiovascular system. Respecting the anti-inflammatory properties of metformin and its favorable impact on the endothelium, it seems to be an interesting option for HDP prophylaxis. The results of previous studies on such use of metformin are ambiguous, although they indicate that in a certain group of pregnant women, it might be effective in preventing hypertensive complications. The aim of this study is to present the possibility of metformin in the prevention of hypertensive disorders of pregnancy with respect to its impact on the pathogenic elements of development

Comparison of Insulin, Metformin, and Glyburide on Perinatal Complications of Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

AIM

This systematic and meta-analysis was conducted to evaluate the efficacy and safety of insulin, metformin, and glyburide on perinatal complications for gestational diabetes mellitus (GDM).

METHODS

Medline (PubMed), EMBASE, The Cochrane Library (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials [CENTRAL], and Cochrane Methodology Register), Web of Science (Science and Social Science Citation Index), and ClinicalTrials (Clinicaltrials.gov) were searched, as well as manual searching. We included randomized controlled trials comparing efficacy and safety of metformin versus glyburide, metformin versus insulin, and glyburide versus insulin in patients with GDM.

RESULTS

We included 32 articles including 5,964 patients published from inception to July 2020. Compared with insulin, metformin was more effective at lower incidence of macrosomia (RR: 0.66, 95% CI: 0.50-0.88, p = 0.005), lower incidence of neonatal intensive care unit admission (RR: 0.78, 95% CI: 0.67-0.91, p = 0.002), less neonatal hypoglycemia (RR: 0.67, 95% CI: 0.56-0.80, p < 0.0001), decreased birth weight (BW) (SMD: -0.37, 95% CI: -0.62 to -0.12, p = 0.004), lower incidence of large for gestational age (RR: 0.76, 95% CI: 0.50-0.90, p = 0.002), shorter gestation age at delivery (MD: -0.22, 95% CI: -0.34 to -0.10, p = 0.0002), lower maternal weight gain (MD: -1.41, 95% CI: -2.28 to -0.55, p = 0.001), less incidence of caesarean section delivery (RR: 0.86, 95% CI: 0.78-0.95, p = 0.0004), lower maternal postprandial blood glucose (SMD: -0.41, 95% CI: -0.72 to -0.11, p = 0.008), and lower incidence of pregnancy-induced hypertension (RR: 0.47, 95% CI: 0.27-0.83, p = 0.01). However, glyburide, compared with insulin, was associated with higher BW (MD: 54.95, 95% CI: 3.87-106.03, p = 0.03) and increased the incidence of neonatal hypoglycemia (RR: 1.52, 95% CI: 1.12-2.07, p = 0.007). Meanwhile, compared to glyburide, metformin was associated with higher maternal fasting blood glucose (SMD: 0.20, 95% CI: 0.05-0.36, p = 0.01) and lower incidence of induction of labor (RR: 0.76, 95% CI: 0.59-0.97, p = 0.03).

CONCLUSIONS

This review suggests that metformin can decrease the incidence of perinatal complications, and it should be considered as a generally safe alternative to insulin.

Impact of metformin treatment during pregnancy on maternal outcomes: a systematic review/meta-analysis

We systematically assessed the impact of metformin treatment on maternal pregnancy outcomes. PubMed, Ovid Embase, Medline, Web of Science, ClinicalTrials.gov and Cochrane databases were systematically searched (inception-1st February 2021). Randomised controlled trials reporting pregnancy outcomes in women randomised to metformin versus any other treatment for any indication were included. Outcomes included gestational weight gain (GWG), pre-eclampsia, gestational hypertension, preterm birth, gestational age at delivery, caesarean section, gestational diabetes, glycaemic control, and gastrointestinal side-effects. Two independent reviewers conducted screening, with a third available to evaluate disagreements. Risk-of-bias and GRADE assessments were conducted using Cochrane Risk-of-Bias and GRADE-pro software. Thirty-five studies (n = 8033 pregnancies) met eligibility criteria. GWG was lower in pregnancies randomised to metformin versus other treatments (1.57 kg ± 0.60 kg; I₂ = 86%, p < 0.0001), as was likelihood of pre-eclampsia (OR 0.69, 95% CI 0.50-0.95; I₂ = 55%, p = 0.02). The risk of gastrointestinal side-effects was greater in metformin-exposed versus other treatment groups (OR 2.43, 95% CI 1.53-3.84; I₂ = 76%, p = 0.0002). The risk of other maternal outcomes assessed was not significantly different between metformin-exposed versus other treatment groups. Metformin for any indication during pregnancy is associated with lower GWG and a modest reduced risk of pre-eclampsia, but increased gastrointestinal side-effects compared to other treatments.

Evaluation of optimum diabetes care on glycemic control of patients with gestational diabetes during Ramadan fasting

AIMS

There is limited evidence that evaluates the impact of fasting during Ramadan in pregnant women. We explored the safety of fasting in Gestational Diabetes Mellitus (GDM) in Ramadan, while understating the glycemic variability.

METHODS

25 patients with GDM who choose to fast, were enrolled and provided optimum care that included Ramadan focused education and FreeStyle LibreFlashContinuous Glucose Monitoring(FSL-CGM) was utilized for 2-4 weeks assessment period of non-Ramadan days plus 2-3 weeks during Ramadan and medication adjustment.

RESULTS

The average glucose improved significantly, while time in target and percent above target numerically improved during Ramadan compared to pre-Ramadan. There was significant increment on the number of hypoglycemic events in Ramadan. The average lowest blood glucose reading reduced significantly by 14 mg/dL with average duration of hypoglycemic events increased significantly by 38.5 min.

CONCLUSION

Our study reinforces the importance of structured education before Ramadan to deliver optimal care for the management of diabetes. Strikingly FSL-CGM demonstrated that hypoglycemia is significantly increased during Ramadan Fasting. There was effective reflection of hyperglycemic spikes, immediately post Iftar. The results corroborated with the earlier studies for higher frequency of hypoglycemia during Ramadan fasting, under similar standards of care in high-risk patients with diabetes.

Progress of Clinical Trials for the Treatment of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is one of the most common and severe complications of pregnancy, which is not only associated with perinatal complications but also has a long-term adverse effect on maternal and their offsprings. At present, the treatment of GDM focuses on the control of maternal blood glucose. Although lifestyle changes, hypoglycemic drugs, blood glucose monitoring, and other medicines that can improve maternal blood glucose to a certain extent, there are still some patients affected and have adverse pregnancy outcomes. The prevention of GDM and the treatment of improving pregnancy outcomes are urgently needed. This review summarized recently published clinical trials related with the treatment of GDM, aiming to provide additional options for the treatment of GDM.

Metformin for prevention of cesarean delivery and large-for-gestational-age newborns in non-diabetic obese pregnant women: a randomized clinical trial

OBJECTIVE

To evaluate the use of metformin for preventing cesarean deliveries and large-for-gestational-age (LGA) newborn (NB) outcomes in non-diabetic obese pregnant women.

SUBJECTS AND METHODS

This is a randomized clinical trial with obese pregnant women, divided into 2 groups: metformin group and control group, with followed-up prenatal routine. The gestational age of participants was less than or equal to 20 weeks and were monitored throughout entire prenatal period. For outcomes of delivery and LGA newborns, absolute risk reduction (ARR) and the number needed to treat (NNT) were calculated with a 95% confidence interval (CI).

RESULTS

357 pregnant women were evaluated. From the metformin group (n = 171), 68 (39.8%) subjects underwent cesarean delivery, and 117 (62.9%) subjects from the control group (n = 186) had intercurrence (p < 0.01). As for the mothers' general characteristics, there was significance for marital status (p < 0.01). Maternal-fetal results presented reduced preeclampsia (p < 0,01). Primary prophylactic results presented an ARR of 23.1 times (95% CI: 13.0-33.4) with NNT of 4 (95% CI: 3.0-7.7) and no significant values for LGA NB (p > 0.01). Secondary prophylactic outcomes presented decreased odds ratio for preeclampsia (OR = 0.17, 95% CI: 0.10-0.41).

CONCLUSION

The use of metformin reduced cesarean section rates, resulted in a small number of patients to be treated, but it did not reduce LGA NB. Administering a lower dosage of metformin from the early stages to the end of treatment may yield significant results with fewer side effects. Arch Endocrinol Metab. 2020;64(3):290-7.

Longer-term outcomes in offspring of GDM mothers treated with metformin versus insulin

Insulin has traditionally been the gold standard pharmacological treatment for gestational diabetes mellitus (GDM). Insulin requires multiple injections a day, can cause frequent hypoglycaemia, requires careful handling, and is generally more expensive compared to oral agents. Metformin has been increasingly popular in recent years. Based on the short-term data available, metformin appears to be safe and effective for the treatment of GDM but existing studies have all stressed the lack of longer-term offspring data. This article will analyse the evidence available on the longer-term outcomes in the offspring of women with GDM treated with metformin versus insulin. Pubmed, EMBASE, CENTRAL, and CNKI were searched for follow-up studies of randomised controlled trials that compared metformin with insulin for the treatment of GDM. Existing follow-up studies did not find any significant increase in the risk of adverse effects in terms of growth and development in the offspring of GDM mothers managed with metformin versus insulin.

The efficacy of metformin compared with insulin in regulating blood glucose levels during gestational diabetes mellitus: A randomized clinical trial

BACKGROUND

Insulin has been a conventional medication in the treatment of female patients suffering from gestational diabetes mellitus (GDM). However, the need for a large number of insulin injections in these patients causes them a lot of discomforts. Recently, an alternative medication, metformin, has received considerable attention in the treatment of GDM. The aim of this study was to compare the efficacy of metformin and insulin in regulating blood glucose levels and fetal outcomes in GDM.

METHODS

This randomized clinical trial included 286 pregnant women diagnosed with positive GDM at 24-28 weeks of pregnancy. The subjects were randomly divided into two groups of 143 patients, with one group receiving insulin and the other undergoing a treatment plan using metformin. Fasting plasma glucose (FPG), 2-hr plasma glucose (PG) and glycated hemoglobin (HbA1c) were recorded twice a month until delivery. Other variables, including birth delivery method, cause of cesarean section, gestational age at the delivery time, birth trauma, Apgar score, birth weight, admission at neonatal intensive care unit (NICU), and neonatal hypoglycemia were also registered.

RESULTS

Age of mother, body mass index, history of diabetes in the family, previous history of GDM, parity, FPG, 1- and 2-hr PG after meals, and 75-g glucose tolerance test before treatment were not statistically different between the two groups. FPG, PG, and HbA1c did not show significant differences between the two groups after completing the course of treatment. There was also no significant difference between two groups regarding the birth delivery method, the cause of cesarean section, birth trauma, Apgar score, birth weight, admission at NICU, and neonatal hypoglycemia.

CONCLUSION

As mean FPG and 2-hr PG were not significantly different between the two groups, it seems that metformin can be recommended as an effective substitute for insulin in the treatment of GDM. However, there are still some undesirable risk factors with both treatments that may threaten the mother and the newborn.

Metformin in the management of diabetes during pregnancy and lactation

This review explores the current place of metformin in the management of gestational diabetes (GDM) and type 2 diabetes during pregnancy and lactation. The rationale and basic pharmacology of metformin usage in pregnancy is discussed along with the evidence from observational and randomized controlled trials in women with GDM or overt diabetes. There seems to be adequate evidence of efficacy and short-term safety of metformin in relation to maternal and neonatal outcomes in GDM, with possible benefits related to lower maternal weight gain and lower risk of neonatal hypoglycemia and macrosomia. Additionally, metformin offers the advantages of oral administration, convenience, less cost and greater acceptability. Metformin may, therefore, be considered in milder forms of GDM where glycemic goals are not attained by lifestyle modification. However, failure rate is likely to be higher in those with an earlier diagnosis of GDM, higher blood glucose, higher body mass index (BMI) or previous history of GDM, and insulin remains the cornerstone of pharmacological treatment in such cases. The use of metformin in type 2 diabetes has been assessed in observational and small randomized trials. Metformin monotherapy in women with overt diabetes is highly unlikely to achieve glycemic targets. Hence, the use should be restricted as adjunct to insulin and may be considered in women with high insulin dose requirements or rapid weight gain. There is clearly a need for more clinical trials to assess the effect of combined insulin plus metformin therapy in pregnancy with type 2 diabetes. Additionally, there is a paucity of data on long-term effects in offspring exposed to metformin in utero. It is imperative to further explore its impact on offspring as metformin has significant transplacental transfer and has the potential to impact the programming of the epigenome. Therefore, caution must be exercised when prescribing metformin in pregnant women. More research is clearly needed before metformin can be considered as standard of care in the management of diabetes during pregnancy.

Comparative efficacy and safety of oral antidiabetic drugs and insulin in treating gestational diabetes mellitus: An updated PRISMA-compliant network meta-analysis

BACKGROUND

The safety and efficacy of different drugs in treatment of gestational diabetes mellitus (GDM) patients who could not maintain normal glucose level only through diet and exercise remains to be debated. We performed this network meta-analysis (NAM) to compare and rank different antidiabetic drugs in glucose level control and pregnancy outcomes in GDM patients.

METHODS

We searched PubMed, Cochrane Library, Web of Science, and Embase up to December 31, 2016. Randomized controlled trials (RCTs) related to different drugs in the treatment of GDM patients were enrolled. We extracted the relevant information and assessed the risk of bias with the Cochrane risk of bias tool. We did pair-wise meta-analyses using the fixed-effects model or random-effects model and then adopted random-effects NAM combining both direct and indirect evidence within a Bayesian framework, to calculate the odds ratio (OR) or standardized mean difference (SMD) and to draw a surface under the cumulative ranking curve of the neonatal and maternal outcomes of different treatments in GDM patients.

RESULTS

Thirty-two randomized controlled trials (RCTs) were included in this NAM, including 6 kinds of treatments (metformin, metformin plus insulin, insulin, glyburide, acarbose, and placebo). The results of the NAM showed that regarding the incidence of macrosomia and LGA, metformin had lower incidence than glyburide (OR, 0.5411 and 0.4177). In terms of the incidence of admission to the NICU, insulin had higher incidence compared with glyburide (OR, 1.844). As for the incidence of neonatal hypoglycemia, metformin had lower incidence than insulin and glyburide (OR, 0.6331 and 0.3898), and insulin was lower than glyburide (OR, 0.6236). For mean birth weight, metformin plus insulin was lower than insulin (SMD, -0.5806), glyburide (SMD, -0.7388), and placebo (SMD, -0.6649). Besides, metformin was observed to have lower birth weight than glyburide (SMD, 0.2591). As for weight gain, metformin and metformin plus insulin were lower than insulin (SMD, -0.9166, -1.53). Ranking results showed that glyburide might be the optimum treatment regarding average glucose control, and metformin is the fastest in glucose control for GDM patients; glyburide have the highest incidence of macrosomia, preeclampsia, hyperbilirubinemia, neonatal hypoglycemia, shortest gestational age at delivery, and lowest mean birth weight; metformin (plus insulin when required) have the lowest incidence of macrosomia, PIH, LGA, RDS, low gestational age at delivery, and low birth weight. Besides, insulin had the highest incidence of NICU admission, acarbose had the lowest risk of neonatal hypoglycemia.

CONCLUSION

Our study concluded that metformin is fastest in glucose control, with a more favorable pregnancy outcomes-would be a better option, but its rate of glucose control is the lowest.However, glyburide is the optimumtreatment regarding the rate of glucose control, but withmore adverse outcomes. This NAMbased on 32 RCTs will strongly help to guide further development of management for GDM patients, clinicians should carefully balance the risk-benefit profile of different treatments according to various situations.

Treatments for gestational diabetes: a systematic review and meta-analysis

OBJECTIVE

To investigate the effectiveness of different treatments for gestational diabetes mellitus (GDM).

DESIGN

Systematic review, meta-analysis and network meta-analysis.

METHODS

Data sources were searched up to July 2016 and included MEDLINE and Embase. Randomised trials comparing treatments for GDM (packages of care (dietary and lifestyle interventions with pharmacological treatments as required), insulin, metformin, glibenclamide (glyburide)) were selected by two authors and double checked for accuracy. Outcomes included large for gestational age, shoulder dystocia, neonatal hypoglycaemia, caesarean section and pre-eclampsia. We pooled data using random-effects meta-analyses and used Bayesian network meta-analysis to compare pharmacological treatments (ie, including treatments not directly compared within a trial).

RESULTS

Forty-two trials were included, the reporting of which was generally poor with unclear or high risk of bias. Packages of care varied in their composition and reduced the risk of most adverse perinatal outcomes compared with routine care (eg, large for gestational age: relative risk0.58 (95% CI 0.49 to 0.68; I2=0%; trials 8; participants 3462). Network meta-analyses suggest that metformin had the highest probability of being the most effective treatment in reducing the risk of most outcomes compared with insulin or glibenclamide.

CONCLUSIONS

Evidence shows that packages of care are effective in reducing the risk of most adverse perinatal outcomes. However, trials often include few women, are poorly reported with unclear or high risk of bias and report few outcomes. The contribution of each treatment within the packages of care remains unclear. Large well-designed and well-conducted trials are urgently needed.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42013004608.

The emerging role of metformin in gestational diabetes mellitus

Metformin use during pregnancy is controversial and there is disparity in the acceptance of metformin treatment in women with gestational diabetes mellitus (GDM) in Australia. Despite short term maternal and neonatal safety measures, the placental transfer of metformin during GDM treatment and the absence of long-term safety data in offspring has regulators and prescribers cautious about its use. To determine the current role in GDM management, this literature review describes the physiological changes that occur in GDM and other forms of diabetes in pregnancy (DIP) and international changes in guidelines for GDM diagnosis. Management options are considered, with a focus on the evolving evidence for metformin, its mechanism of action, the maternal, foetal and neonatal outcomes associated with its use and benefit vs risk when compared with the current gold standard, insulin. Investigation reveals a favourable balance of evidence to support the safety and long-term benefits, to mother and child, of using metformin as an alternate to insulin for treatment of GDM. Recent findings of the gastrointestinal-directed action of metformin are at least as important as the hepatic effect and the availability of a novel delayed-release metformin dose form to exploit this new information provides a product and therapeutic strategy ideally suited to the use of metformin in GDM.

The effects of prenatal metformin on obesogenic diet-induced alterations in maternal and fetal fatty acid metabolism

Background

Maternal obesity may program the fetus and increase the susceptibility of the offspring to adult diseases. Metformin crosses the placenta and has been associated with decreased inflammation and reversal of fatty liver in obese leptin-deficient mice. We investigated the effects of metformin on maternal and fetal lipid metabolism and hepatic inflammation using a rat model of diet-induced obesity during pregnancy.

Methods

Female Wistar rats (6–7 weeks old) were fed normal or high calorie diets for 5 weeks. After mating with normal-diet fed males, half of the high calorie-fed dams received metformin (300 mg/kg, daily); dams (8 per group) continued diets through gestational day 19. Maternal and fetal livers and fetal brains were analyzed for fatty acids and for fatty acid metabolism-related gene expression. Data were analyzed by ANOVA followed by Dunnett’s post hoc testing.

Results

When compared to control-lean maternal livers, obesogenic-diet-exposed maternal livers showed significantly higher saturated fatty acids (14:0 and 16:0) and monounsaturated fatty acids (16:1n7 and 18:1n9) and lower polyunsaturated (18:2n6 and 20:4n6 [arachidonic acid]) and anti-inflammatory n3 polyunsaturated fatty acids (18:3n3 and 22:6n3 [docosahexaenoic acid]) (p < 0.05). Metformin did not affect diet-induced changes in maternal livers. Fetal livers exposed to the high calorie diet showed significantly increased saturated fatty acids (18:0) and monounsaturated fatty acids (18:1n9 and 18:1n7) and decreased polyunsaturated fatty acids (18:2n6, 20:4n6 and 22:6n3) and anti-inflammatory n3 polyunsaturated fatty acids, along with increased gene expression of fatty acid metabolism markers (Fasn, D5d, D6d, Scd1, Lxrα). Metformin significantly attenuated diet-induced inflammation and 18:1n9 and 22:6n3 in fetal livers, as well as n3 fatty acids (p < 0.05). Prenatal obesogenic diet exposure significantly increased fetal liver IFNγ levels (p < 0.05), which was reversed by maternal metformin treatment (p < 0.05).

Conclusions

Consumption of a high calorie diet significantly affected maternal and fetal fatty acid metabolism. It reduced anti-inflammatory polyunsaturated fatty acids in maternal and fetal livers, altered gene expression of fatty acid metabolism markers, and induced inflammation in the fetal livers. Prenatal metformin attenuated some diet-induced fatty acid changes and inflammation in the fetal livers without affecting maternal livers, suggesting that maternal metformin may impact fetal/neonatal fatty acid/lipid metabolism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0115-9) contains supplementary material, which is available to authorized users.