Could Metformin Manage Gestational Diabetes Mellitus instead of Insulin?

Metformin in gestational diabetes: physiological actions and clinical applications

Metformin is an effective oral hypoglycaemic agent used in the treatment of type 2 diabetes mellitus; however, its use in pregnancy for the treatment of gestational diabetes mellitus (GDM) remains controversial owing to concerns around safety and efficacy. This comprehensive review outlines the physiological metabolic functions of metformin and synthesizes existing literature and key knowledge gaps pertaining to the use of metformin in pregnancy across various end points in women with GDM. On the basis of current evidence, metformin reduces gestational weight gain, neonatal hypoglycaemia and macrosomia and increases insulin sensitivity. However, considerable heterogeneity between existing studies and the grouping of aggregate and often inharmonious data within meta-analyses has led to disparate findings regarding the efficacy of metformin in treating hyperglycaemia in GDM. Innovative analytical approaches with stratification by individual-level characteristics (for example, obesity, ethnicity, GDM severity and so on) and treatment regimens (diagnostic criteria, treatment timing and follow-up duration) are needed to establish efficacy across a range of end points and to identify which, if any, subgroups might benefit from metformin treatment during pregnancy.

A meta-analysis of metformin and insulin on maternal outcome and neonatal outcome in patients with gestational diabetes mellitus

INTRODUCTION

The use of metformin for treating gestational diabetes mellitus (GDM) remains controversial because it can pass through the placenta. This meta-analysis aimed to compare the effects of metformin and insulin on maternal and neonatal outcomes in patients with GDM.

METHODS

We conducted a comprehensive search of the PubMed, Embase, and Cochrane Library databases, focusing on randomized controlled trials (RCTs) that evaluated the impacts of metformin and insulin on both maternal and neonatal outcomes in patients with GDM.

RESULTS

Twenty-four RCTs involving 4934 patients with GDM were included in this meta-analysis. Compared with insulin, metformin demonstrated a significant reduction in the risks of preeclampsia (RR 0.61, 95% CI 0.48 to 0.78, p < .0001), induction of labor (RR 0.90, 95% CI 0.82 to 0.98, p = .02), cesarean delivery (RR 0.91, 95% CI 0.85 to 0.98, p = .01), macrosomia (RR 0.67, 95% CI 0.53 to 0.83, p = .0004), neonatal intensive care unit (NICU) admission (RR 0.75, 95% CI 0.66 to 0.86, p < .0001), neonatal hypoglycemia (RR 0.55, 95% CI 0.48 to 0.63, p < .00001), and large for gestational age (LGA) (RR 0.80, 95% CI 0.68 to 0.94, p = .007). Conversely, metformin showed no significant impact on gestational hypertension (RR 0.84, 95% CI 0.67 to 1.06, p = .15), spontaneous vaginal delivery (RR 1.13, 95% CI 1.00 to 1.08, p = .05), emergency cesarean section (RR 0.94, 95% CI 0.77 to 1.16, p = .58), shoulder dystocia (RR 0.65, 95% CI 0.31 to 1.39, p = .27), premature birth (RR 0. 92, 95% CI 0.61 to 1.39, p = .69), polyhydramnios (RR 1.11, 95% CI 0.54 to 2.30, p = .77), birth trauma (RR 0.87, 95% CI 0.54 to 1.39, p = .56), 5-min Apgar score < 7 (RR 1.13, 95% CI 0.76 to 1.68, p = .55), small for gestational age (SGA) (RR 0.93, 95% CI 0.71 to 1.22, p = .62), respiratory distress syndrome (RDS) (RR 0.74, 95% CI 0.50 to 1.08, p = .11), jaundice (RR 1.09, 95% CI 0.95 to 1.25, p = .24) or birth defects (RR 0.80, 95% CI 0.37 to 1.74, p = .57).

CONCLUSIONS

The findings suggest that metformin can reduce the risk of certain maternal and neonatal outcomes compared with insulin therapy for GDM. However, long-term follow-up studies of patients with GDM taking metformin and their offspring are warranted to provide further evidence.

Short-term neonatal outcomes in women with gestational diabetes treated using metformin versus insulin: a systematic review and meta-analysis of randomized controlled trials

AIMS

To expand the evidence base for the clinical use of metformin, we conducted a meta-analysis of randomized controlled trials (RCTs) comparing the efficacy and safety of metformin versus insulin with respect to short-term neonatal outcomes.

METHODS

A comprehensive search of electronic databases (PubMed, Embase, Cochrane Library, and Web of Science) was performed. Two reviewers extracted the data and calculated pooled estimates by use of a random-effects model. In total, 24 studies involving 4355 participants met the eligibility criteria and were included in the quantitative analyses.

RESULTS

Unlike insulin, metformin lowered neonatal birth weights (mean difference - 122.76 g; 95% confidence interval [CI] - 178.31, - 67.21; p < 0.0001), the risk of macrosomia (risk ratio [RR] 0.68; 95% CI 0.54, 0.86; p = 0.001), the incidence of neonatal intensive care unit admission (RR 0.73; 95% CI 0.61, 0.88; p = 0.0009), and the incidence of neonatal hypoglycemia (RR 0.65; 95% CI 0.52, 0.81; p = 0.0001). Subgroup analysis based on the maximum daily oral dose of metformin indicated that metformin-induced neonatal birth weight loss was independent of the oral dose.

CONCLUSIONS

Our meta-analysis provides further evidence that metformin is a safe oral antihyperglycemic drug and has some benefits over insulin when used for the treatment of gestational diabetes, without an increased risk of short-term neonatal adverse outcomes. Metformin may be particularly useful in women with gestational diabetes at high risk for neonatal hypoglycemia, women who want to limit maternal and fetal weight gain, and women with an inability to afford or use insulin safely.

Comparison of the effectiveness and safety of insulin and oral hypoglycemic drugs in the treatment of gestational diabetes mellitus: a meta-analysis of 26 randomized controlled trials

OBJECTIVE

Oral hypoglycemic drugs for the treatment of gestational diabetes mellitus (GDM) are still controversial because they can pass through the placenta. The purpose of this meta-analysis is to evaluate the safety and effectiveness of oral hypoglycemic drugs.

METHODS

PubMed, Ovid Embase, Web of Science, and Cochrane databases were systematically searched (inception to 20 April 2021). Rev Man 5.0 was used to analyze the data. A random-effects model was used to compute the summary risk estimates.

RESULTS

There were 26 randomized controlled trials (RCTs) involving 4921 GDM patients which were included in this meta-analysis. Compared with metformin, insulin had a significant increase in the risk of preeclampsia (odds ratio [OR], 1.61; 95% confidence interval [CI], 1.06 to 2.45; I²=40%; p < .05), hypertension (OR, 1.42; 95% CI, 1.02 to 1.99; I²=0%; p < .05), hypoglycemia (OR, 3.93; 95% CI, 1.27 to 12.19; I²=0%; p < .05), neonatal hypoglycemia (OR, 1.92; 95% CI, 1.34 to 2.76; I²=41%; p < .0001), neonatal jaundice (OR, 2.70; 95% CI, 1.12 to 6.52; I²=0%; p < .05), and Neonatal Intensive Care Unit Admission (OR, 1.46; 95% CI, 1.09 to 1.95; I²=39%; p < .05), but the risk of neonatal macrosomia (OR, 1.67; 95% CI, 1.12 to 2.40; I²=0%; p < .05) and neonatal injury (OR, 0.70; 95% CI, 0.55 to 0.89; I²=0%; p < .01) is lower.

CONCLUSIONS

Metformin is comparable with insulin in glycemic control and neonatal outcomes and has the potential to replace insulin therapy in clinical practice. Glyburide is behind metformin and insulin, and more RCTs are needed to verify its safety.

Glycemic control and neonatal outcomes in women with gestational diabetes mellitus treated using glyburide, metformin, or insulin: a pairwise and network meta-analysis

AIMS

We aimed to assess the comparative efficiency and safety of the use of glyburide, metformin, and insulin in gestational diabetes mellitus (GDM).

METHODS

We searched for randomized controlled trials that compared glyburide, metformin, and insulin in GDM. Data regarding glycemic control and neonatal safety were collected and analyzed in pairwise and network meta-analyses.

RESULTS

A total of 4533 individuals from 23 trials were included. Compared with glyburide, metformin reduced 2-h postprandial blood glucose (2HPG) to a greater extent (standard mean difference (SMD) 0.18; 95% credible interval (CI) 0.01, 0.34). There were significantly lower prevalence of neonatal hypoglycemia (risk difference (RD) - 0.07; 95%CI - 0.11, - 0.02) and preeclampsia (RD - 0.03; 95%CI - 0.06, 0) in the metformin group than in the insulin group. The metformin group had significantly lower birth weight (SMD - 0.17; 95%CI - 0.25, - 0.08) and maternal weight gain (SMD - 0.61; 95%CI - 0.86,- 0.35) compared with the insulin group. Network meta-analysis suggested that metformin had the highest probability of successfully controlling glycemia and preventing neonatal complications.

CONCLUSIONS

The present meta-analysis suggests that metformin may be as effective as insulin for glycemic control and is the most promising drug for the prevention of neonatal and maternal complications.

Effects of Different Glucose-Lowering Measures on Maternal and Infant Outcomes in Pregnant Women with Gestational Diabetes: A Network Meta-analysis

INTRODUCTION

A network meta-analysis was conducted to compare and rank the effects of different glucose-lowering measures on maternal and infant outcomes in pregnant women with gestational diabetes mellitus (GDM).

METHODS

We searched the PubMed, CNKI, Embase, Cochrane Library, Wanfang, and Weipu databases for relevant studies published between database establishment and June 2021. Study retrieval involved subject-heading and keyword searches. Randomized controlled trials (RCTs) with different glucose-lowering treatments for GDM patients were included. The Cochrane tool was used to assess bias risk. Pairwise and network meta-analyses were used to compare and rank the effects of different hypoglycemic measures on maternal and infant outcomes in pregnant women with GDM.

RESULTS

We included 41 RCTs involving 6245 pregnant women with GDM. Patients treated with insulin had a higher incidence of neonatal intensive care unit (NICU) occupancy (1.3, 95% CI 1.0-1.7) than those treated with metformin. The insulin (1.5, 95% CI 1.1-2.1 and 1.8, 95% CI 1.0-3.3) and glyburide (2.0, 95% CI 1.2-3.2 and 2.5, 95% CI 1.1-8.4) groups exhibited higher incidences of neonatal hypoglycemia and large for gestational age (LGA) newborns than the metformin group. The glyburide group exhibited a lower probability of cesarean section than the metformin (0.76, 95% CI 0.55-1.0) and insulin (0.71, 95% CI 0.52-0.96) groups. Preeclampsia incidence in the diet and exercise groups was significantly lower than in the metformin (0.19, 95% CI 0.043-0.72) and insulin (0.15, 95% CI 0.032-0.52) groups. No intervention significantly reduced the incidences of macrosomia, preterm birth, gestational hypertension, or respiratory distress syndrome (RDS). The ranking results showed that the metformin group had the lowest rates of neonatal hypoglycemia, macrosomia, LGA, and NICU occupancy. The glyburide group had the lowest NICU occupancy and cesarean section rates and the highest neonatal hypoglycemia, LGA, preeclampsia, and gestational hypertension rates. The diet and exercise group had the lowest preterm delivery and preeclampsia rates and the highest NICU occupancy rate.

CONCLUSION

Metformin is a potentially superior choice for GDM treatment because it is associated with minimal incidences of multiple adverse pregnancy outcome indicators and does not lead to high values of certain adverse outcome indices. Other hypoglycemic agent or diet groups exhibit high incidences of certain adverse outcomes. Therefore, when selecting a GDM treatment strategy, the efficacies and risks of different treatment programs should be evaluated according to the scenario in hand.

The effects of insulin therapy on maternal blood pressure and weight in women with gestational diabetes mellitus

Background

Although insulin therapy achieves effective glycemic control, it may aggravate hyperinsulinemia. Nonetheless the benefits of insulin as first-line treatment for women with GDM are controversial. This work aimed to investigate the effect of insulin on maternal GDM.

Methods

This retrospective cohort study recruited 708 women with GDM of whom 616 underwent lifestyle intervention and 92 were prescribed insulin therapy. Differences in variables between the two groups were analyzed by univariate analysis and multivariate analysis. Propensity score matching was used to control for age, pre-pregnancy BMI, time and BP at GDM diagnosis, and family history of diabetes and hypertension. Paired sample test was applied to evaluate the changes in BP after intervention in the two groups of women.

Results

There was no significant difference in mode of delivery, newborn weight or incidence of macrosomia between women prescribed insulin and those who adopted lifestyle modifications. Insulin therapy was associated with a slight increase in maternal weight compared with the lifestyle intervention group and was attributed to short-term treatment (about 12 weeks). In addition, insulin therapy remarkably increased maternal blood pressure, an effect that persisted after matching age, pre-pregnancy BMI, time and BP at GDM diagnosis, and family history of diabetes and hypertension. Between commencing insulin therapy and delivery, systolic blood pressure significantly increased by 6mmHg (P = 0.015) and diastolic blood pressure by 9 mmHg (P < 0.001). Increase in BP was significantly higher in the insulin group compared with the lifestyle intervention group (P < 0.001). Logistic regression analysis with enter selection confirmed that insulin therapy was closely correlated with development of gestational hypertension (GH).

Conclusions

This work suggested that short-term insulin therapy for GDM was associated with a slight increase in maternal weight but a significant risk of increasing maternal blood pressure.

The efficacy and safety of metformin alone or as an add-on therapy to insulin in pregnancy with GDM or T2DM: A systematic review and meta-analysis of 21 randomized controlled trials

WHAT IS KNOWN AND OBJECTIVE

Pregnant women are increasingly being exposed to metformin for conditions including gestational diabetes mellitus and type 2 diabetes mellitus. Metformin has been found to exhibit maternal to foetal transfer, and the long-term influence is uncertain. We conducted a meta-analysis to compare the efficacy and safety of metformin alone or as add-on therapy to insulin and insulin in pregnancy with gestational diabetes mellitus or type 2 diabetes mellitus.

METHODS

We performed a comprehensive literature search of PubMed, Embase, Cochrane Library and ClinicalTrials.gov for randomized controlled trials (RCTs) that compared metformin to insulin in pregnancy. Risk ratios (RRs) and mean differences (MDs) with 95% confidence intervals (CIs) were used to synthesize the results. Two authors independently extracted the data, evaluated study quality and calculated pooled estimates.

RESULTS

Twenty-one studies involving 4,545 patients were included in this meta-analysis. Compared with insulin, metformin significantly reduced the risks of maternal weight gain [MD -1.51 kg, 95%CI (-1.90 kg, -1.12 kg), P < 0.00001], gestational age at birth [MD -0.12 week, 95%CI (-0.21 week, -0.02 week), P = 0.02], gestational hypertension [RR 0.63, 95%CI (0.48, 0.82), P = 0.0006], maternal hypoglycaemia [RR 0.33, 95%CI (0.15, 0.73), P = 0.006], birthweight [MD -0.13 kg, 95%CI (-0.20 kg, -0.07 kg), P < 0.0001], neonatal hypoglycaemia [RR 0.56, 95%CI (0.49, 0.64), P < 0.00001], neonatal intensive care unit admission [RR 0.73, 95%CI (0.64, 0.83), P < 0.00001], birthweight ≥4000 g [RR 0.70, 95%CI (0.59, 0.83), P < 0.0001], and large for gestational age [RR 0.83, 95%CI (0.72, 0.97), P = 0.02] and significantly increased the risk of small for gestational age [RR 1.43, 95%CI (1.08, 1.89), P = 0.01] in pregnancy.

WHAT IS NEW AND CONCLUSION

Metformin may have potential benefits for pregnant women and newborns in terms of maternal and foetal outcomes. More studies with long-term follow-up of offspring exposed to metformin in utero are needed to provide evidence for the future use of metformin in pregnancy.

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.

Metformin is comparable to insulin for pharmacotherapy in gestational diabetes mellitus: A network meta-analysis evaluating 6046 women

CONTEXT

The comparative efficacy of gestational diabetes (GDM) treatments lack conclusive evidence for choice of first-line treatment.

OBJECTIVES

The aim of this study was to compare the efficacy of metformin and glibenclamide to insulin using a core outcome set (COS) to unify outcomes across trials investigating the treatment of gestational diabetes mellitus.

STUDY DESIGN

A network meta-analysis (NMA) was conducted.

DATA-SOURCE

PubMed, Embase, and Cochrane Controlled Register of Trials were searched from inception to January 2020.

STUDY SELECTION

RCTs that enrolled pregnant women who were diagnosed with GDM and that compared the efficacy of different pharmacological interventions for the treatment of GDM were included.

META-ANALYSIS

A generalized pairwise modelling framework was employed.

RESULTS

A total of 38 RCTs with 6046 participants were included in the network meta-analysis. Compared to insulin, the estimated effect of metformin indicated improvements for weight gain (WMD -2·39 kg; 95% CI -3·31 to -1·46), maternal hypoglycemia (OR 0.34; 95% CI 0.12 to 0·97) and LGA (OR 0.61; 95% CI 0.38 to 0·98). There were also improvements in estimated effects for neonatal hypoglycemia (OR 0.48; 95% CI 0.19 to 1·25), pregnancy induced hypertension (OR 0.63; 95% CI 0.37 to 1·06), and preeclampsia (OR 0.74; 95% CI 0.538 to 1·04), though with limited evidence against our model hypothesis of equivalence with insulin for these outcomes.

CONCLUSION

Metformin is, at least, comparable to insulin for the treatment of GDM. Glibenclamide appears less favorable, in comparison to insulin, than metformin.

Comparative impact of pharmacological treatments for gestational diabetes on neonatal anthropometry independent of maternal glycaemic control: A systematic review and meta-analysis

BACKGROUND

Fetal growth in gestational diabetes mellitus (GDM) is directly linked to maternal glycaemic control; however, this relationship may be altered by oral anti-hyperglycaemic agents. Unlike insulin, such drugs cross the placenta and may thus have independent effects on fetal or placental tissues. We investigated the association between GDM treatment and fetal, neonatal, and childhood growth.

METHODS AND FINDINGS

PubMed, Ovid Embase, Medline, Web of Science, ClinicalTrials.gov, and Cochrane databases were systematically searched (inception to 12 February 2020). Outcomes of GDM-affected pregnancies randomised to treatment with metformin, glyburide, or insulin were included. Studies including preexisting diabetes or nondiabetic women were excluded. Two reviewers independently assessed eligibility and risk of bias, with conflicts resolved by a third reviewer. Maternal outcome measures were glycaemic control, weight gain, and treatment failure. Offspring anthropometric parameters included fetal, neonatal, and childhood weight and body composition data. Thirty-three studies (n = 4,944), from geographical locations including Europe, North Africa, the Middle East, Asia, Australia/New Zealand, and the United States/Latin America, met eligibility criteria. Twenty-two studies (n = 2,801) randomised women to metformin versus insulin, 8 studies (n = 1,722) to glyburide versus insulin, and 3 studies (n = 421) to metformin versus glyburide. Eleven studies (n = 2,204) reported maternal outcomes. No differences in fasting blood glucose (FBS), random blood glucose (RBS), or glycated haemoglobin (HbA1c) were reported. No studies reported fetal growth parameters. Thirty-three studies (n = 4,733) reported birth weight. Glyburide-exposed neonates were heavier at birth (58.20 g, 95% confidence interval [CI] 10.10-106.31, p = 0.02) with increased risk of macrosomia (odds ratio [OR] 1.38, 95% CI 1.01-1.89, p = 0.04) versus neonates of insulin-treated mothers. Metformin-exposed neonates were born lighter (-73.92 g, 95% CI -114.79 to -33.06 g, p < 0.001) with reduced risk of macrosomia (OR 0.60, 95% CI 0.45-0.79, p < 0.001) than insulin-exposed neonates. Metformin-exposed neonates were born lighter (-191.73 g, 95% CI -288.01 to -94.74, p < 0.001) with a nonsignificant reduction in macrosomia risk (OR 0.32, 95% CI 0.08-1.19, I2 = 0%, p = 0.09) versus glyburide-exposed neonates. Glyburide-exposed neonates had a nonsignificant increase in total fat mass (103.2 g, 95% CI -3.91 to 210.31, p = 0.06) and increased abdominal (0.90 cm, 95% CI 0.03-1.77, p = 0.04) and chest circumferences (0.80 cm, 95% CI 0.07-1.53, p = 0.03) versus insulin-exposed neonates. Metformin-exposed neonates had decreased ponderal index (-0.13 kg/m3, 95% CI -0.26 to -0.00, p = 0.04) and reduced head (-0.21, 95% CI -0.39 to -0.03, p = 0.03) and chest circumferences (-0.34 cm, 95% CI -0.62 to -0.05, p = 0.02) versus the insulin-treated group. Metformin-exposed neonates had decreased ponderal index (-0.09 kg/m3, 95% CI -0.17 to -0.01, p = 0.03) versus glyburide-exposed neonates. Study limitations include heterogeneity in dosing, heterogeneity in GDM diagnostic criteria, and few studies reporting longitudinal growth outcomes.

CONCLUSIONS

Maternal randomisation to glyburide resulted in heavier neonates with a propensity to increased adiposity versus insulin- or metformin-exposed groups. Metformin-exposed neonates were lighter with reduced lean mass versus insulin- or glyburide-exposed groups, independent of maternal glycaemic control. Oral anti-hyperglycaemics cross the placenta, so effects on fetal anthropometry could result from direct actions on the fetus and/or placenta. We highlight a need for further studies examining the effects of intrauterine exposure to antidiabetic agents on longitudinal growth, and the importance of monitoring fetal growth and maternal glycaemic control when treating GDM. This review protocol was registered with PROSPERO (CRD42019134664/CRD42018117503).

Metformin versus insulin for gestational diabetes: a systematic review and meta-analysis

BACKGROUND

Metformin is increasingly used in clinical practice for the treatment of gestational diabetes mellitus. However, its safety and long-term effects on fetuses exposed to metformin in uterus remain controversial.

METHODS

We systematically searched PubMed, Embase, and the Cochrane database (last search was updated on 1 May 2019) for randomized controlled trials comparing metformin with insulin. Two reviewers extracted the data and calculated pooled estimates by use of a random-effects model.

RESULTS

Twenty-four studies were included. Among these, seventeen RCTs (N = 2828 participants) were included for quantitative analyses and seven studies were included only for qualitative synthesis. Metformin lowered the risk of pregnancy-induced hypertension (p = .03; risk ratio (RR) = 0.64; confidence interval (95%CI) [0.44, 0.95]), large for gestational age babies (p = .04; RR = 0.82; 95% CI [0.68, 0.99]), macrosomia (p = .01; RR = 0.63; 95%CI [0.45, 0.90]), neonatal hypoglycemia (p = .001; RR = 0.72; 95%CI [0.59, 0.88]), and neonatal intensive care unit admission (p = .01; RR = 0.74; 95%CI [0.58, 0.94]). Metformin did not increase premature delivery (p = .11; RR = 1.28; 95%CI [0.95, 1.73]), preeclampsia (p = .45; RR = 0.89; 95%CI [0.65, 1.21]), caesarean delivery (p = .20; RR = 0.94; 95%CI [0.85, 1.04]), small for gestational age babies (p = .95; RR = 0.99; 95%CI [0.69, 1.42]). The long-term results seemed to have no adverse effect, but the information was still limited.

CONCLUSIONS

According to our review, metformin may have potential benefits for pregnant women and newborns with no obvious adverse effects. However, even more studies are needed to provide evidence for the future use of metformin.

Neonatal, infant, and childhood growth following metformin versus insulin treatment for gestational diabetes: A systematic review and meta-analysis

BACKGROUND

Metformin is increasingly offered as an acceptable and economic alternative to insulin for treatment of gestational diabetes mellitus (GDM) in many countries. However, the impact of maternal metformin treatment on the trajectory of fetal, infant, and childhood growth is unknown.

METHODS AND FINDINGS

PubMed, Ovid Embase, Medline, Web of Science, ClinicalTrials.gov, and the Cochrane database were systematically searched (from database inception to 26 February 2019). Outcomes of GDM-affected pregnancies randomised to treatment with metformin versus insulin were included (randomised controlled trials and prospective randomised controlled studies) from cohorts including European, American, Asian, Australian, and African women. Studies including pregnant women with pre-existing diabetes or non-diabetic women were excluded, as were trials comparing metformin treatment with oral glucose-lowering agents other than insulin. Two reviewers independently assessed articles for eligibility and risk of bias, and conflicts were resolved by a third reviewer. Outcome measures were parameters of fetal, infant, and childhood growth, including weight, height, BMI, and body composition. In total, 28 studies (n = 3,976 participants) met eligibility criteria and were included in the meta-analysis. No studies reported fetal growth parameters; 19 studies (n = 3,723 neonates) reported measures of neonatal growth. Neonates born to metformin-treated mothers had lower birth weights (mean difference -107.7 g, 95% CI -182.3 to -32.7, I2 = 83%, p = 0.005) and lower ponderal indices (mean difference -0.13 kg/m3, 95% CI -0.26 to 0.00, I2 = 0%, p = 0.04) than neonates of insulin-treated mothers. The odds of macrosomia (odds ratio [OR] 0.59, 95% CI 0.46 to 0.77, p < 0.001) and large for gestational age (OR 0.78, 95% CI 0.62 to 0.99, p = 0.04) were lower following maternal treatment with metformin compared to insulin. There was no difference in neonatal height or incidence of small for gestational age between groups. Two studies (n = 411 infants) reported measures of infant growth (18-24 months of age). In contrast to the neonatal phase, metformin-exposed infants were significantly heavier than those in the insulin-exposed group (mean difference 440 g, 95% CI 50 to 830, I2 = 4%, p = 0.03). Three studies (n = 520 children) reported mid-childhood growth parameters (5-9 years). In mid-childhood, BMI was significantly higher (mean difference 0.78 kg/m2, 95% CI 0.23 to 1.33, I2 = 7%, p = 0.005) following metformin exposure than following insulin exposure, although the difference in absolute weights between the groups was not significantly different (p = 0.09). Limited evidence (1 study with data treated as 2 cohorts) suggested that adiposity indices (abdominal [p = 0.02] and visceral [p = 0.03] fat volumes) may be higher in children born to metformin-treated compared to insulin-treated mothers. Study limitations include heterogeneity in metformin dosing, heterogeneity in diagnostic criteria for GDM, and the scarcity of reporting of childhood outcomes.

CONCLUSIONS

Following intrauterine exposure to metformin for treatment of maternal GDM, neonates are significantly smaller than neonates whose mothers were treated with insulin during pregnancy. Despite lower average birth weight, metformin-exposed children appear to experience accelerated postnatal growth, resulting in heavier infants and higher BMI by mid-childhood compared to children whose mothers were treated with insulin. Such patterns of low birth weight and postnatal catch-up growth have been reported to be associated with adverse long-term cardio-metabolic outcomes. This suggests a need for further studies examining longitudinal perinatal and childhood outcomes following intrauterine metformin exposure. This review protocol was registered with PROSPERO under registration number CRD42018117503.

Comparative Efficacy and Safety of Metformin, Glyburide, and Insulin in Treating Gestational Diabetes Mellitus: A Meta-Analysis

To compare the efficacy and safety of metformin, glyburide, and insulin in treating gestational diabetes mellitus (GDM), a meta-analysis of randomized controlled trials (RCTs) was conducted. PubMed, Embase, CINAHL, Web of Science, and Cochrane Library to November 13, 2018, were searched for RCT adjusted estimates of the efficacy and safety of metformin, glyburide, and insulin treatments in GDM patients. There were 41 studies involving 7703 GDM patients which were included in this meta-analysis; 12 primary outcomes and 24 secondary outcomes were detected and analyzed. Compared with metformin, insulin had a significant increase in the risk of preeclampsia (RR, 0.57; 95% CI, 0.45 to 0.72; P < 0.001), NICU admission (RR, 0.75; 95% CI, 0.64 to 0.87; P < 0.001), neonatal hypoglycemia (RR, 0.57; 95% CI, 0.49 to 0.66; P < 0.001), and macrosomia (RR, 0.68; 95% CI, 0.55 to 0.86; P < 0.05). To the outcomes of birth weight and gestational age at delivery, insulin had a significant increase when compared with metformin (MD, 114.48; 95% CI, 37.32 to 191.64; P < 0.01; MD, 0.23; 95% CI, 0.12 to 0.34; P < 0.001; respectively). Of the two groups between glyburide and metformin, metformin had lower gestational weight gain compared with glyburide (MD, 1.67; 95% CI, 0.26 to 3.07; P < 0.05). Glyburide had a higher risk of neonatal hypoglycemia compared with insulin (RR, 1.76; 95% CI, 1.32 to 2.36; P < 0.001). This meta-analysis found that metformin could be a safe and effective treatment for GDM. However, clinicians should pay attention on the long-term offspring outcomes of the relative data with GDM patients treated with metformin. Compared with insulin, glyburide had a higher increase of neonatal hypoglycemia. The use of glyburide in pregnancy for GDM women appears to be unclear.

Metformin for prevention of hypertensive disorders of pregnancy in women with gestational diabetes or obesity: systematic review and meta-analysis of randomized trials

OBJECTIVE

Metformin has been reported to reduce the risk of pre-eclampsia. It is also known to influence soluble fms-like tyrosine kinase-1 level, which correlates significantly with the gestational age at onset and severity of pre-eclampsia. The main aim of this systematic review and meta-analysis of randomized trials was to determine whether metformin use is associated with the incidence of hypertensive disorders of pregnancy (HDP).

METHODS

MEDLINE (1947 to September 2017), Scopus (1970 to September 2017) and the Cochrane Library (inception to September 2017) were searched for relevant citations in the English language. Only randomized controlled trials on metformin use, reporting the incidence of pre-eclampsia or pregnancy-induced hypertension, were included. Studies on populations with a high probability of metformin use prior to randomization (those with type II diabetes or polycystic ovary syndrome) were excluded. Random-effects models with the Mantel-Haenszel method were used for subgroup analyses. Bayesian random-effects meta-regression was used to summarize the evidence.

RESULTS

In total, 3337 citations matched the search criteria. After evaluating 2536 abstracts and performing full-text review of 52 studies, 15 were included in the review. In women with gestational diabetes, metformin use was associated with a reduced risk of pregnancy-induced hypertension when compared with insulin (relative risk (RR), 0.56; 95% CI, 0.37-0.85; I²  = 0%; 1260 women) and a non-significantly reduced risk of pre-eclampsia (RR, 0.83; 95% CI, 0.60-1.14; I²  = 0%; 1724 women). In obese women, when compared with placebo, metformin use was associated with a non-significant reduction in risk of pre-eclampsia (RR, 0.74; 95% CI, 0.09-6.28; I²  = 86%; 840 women). In women with gestational diabetes, metformin use was also associated with a non-significant reduction in risk of any HDP (RR, 0.71; 95% CI, 0.41-1.25; I²  = 0%; 556 women) when compared with glyburide. When studies were combined using Bayesian random-effects meta-regression, with treatment type as a covariate, the posterior probabilities of metformin having a beneficial effect on the prevention of pre-eclampsia, pregnancy-induced hypertension and any HDP were 92.7%, 92.8% and 99.2%, respectively, when compared with any other treatment or placebo.

CONCLUSIONS

There is a high probability that metformin use is associated with reduced HDP incidence when compared with other treatments or placebo. The small number of studies included in the analysis, the low quality of evidence and the clinical heterogeneity preclude generalization of these results to broader populations. Given the clinical importance of this topic and the magnitude of effect observed in this meta-analysis, further prospective trials are urgently needed. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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.

Insulin for the treatment of women with gestational diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with short- and long-term complications for the mother and her infant. Women who are unable to maintain their blood glucose concentration within pre-specified treatment targets with diet and lifestyle interventions will require anti-diabetic pharmacological therapies. This review explores the safety and effectiveness of insulin compared with oral anti-diabetic pharmacological therapies, non-pharmacological interventions and insulin regimens.

OBJECTIVES

To evaluate the effects of insulin in treating women with gestational diabetes.

SEARCH METHODS

We searched Pregnancy and Childbirth's Trials Register (1 May 2017), ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP) (1 May 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (including those published in abstract form) comparing:a) insulin with an oral anti-diabetic pharmacological therapy;b) with a non-pharmacological intervention;c) different insulin analogues;d) different insulin regimens for treating women with diagnosed with GDM.We excluded quasi-randomised and trials including women with pre-existing type 1 or type 2 diabetes. Cross-over trials were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, risk of bias, and extracted data. Data were checked for accuracy.

MAIN RESULTS

We included 53 relevant studies (103 publications), reporting data for 7381 women. Forty-six of these studies reported data for 6435 infants but our analyses were based on fewer number of studies/participants.Overall, the risk of bias was unclear; 40 of the 53 included trials were not blinded. Overall, the quality of the evidence ranged from moderate to very low quality. The primary reasons for downgrading evidence were imprecision, risk of bias and inconsistency. We report the results for our maternal and infant GRADE outcomes for the main comparison. Insulin versus oral anti-diabetic pharmacological therapyFor the mother, insulin was associated with an increased risk for hypertensive disorders of pregnancy (not defined) compared to oral anti-diabetic pharmacological therapy (risk ratio (RR) 1.89, 95% confidence interval (CI) 1.14 to 3.12; four studies, 1214 women; moderate-quality evidence). There was no clear evidence of a difference between those who had been treated with insulin and those who had been treated with an oral anti-diabetic pharmacological therapy for the risk of pre-eclampsia (RR 1.14, 95% CI 0.86 to 1.52; 10 studies, 2060 women; moderate-quality evidence); the risk of birth by caesarean section (RR 1.03, 95% CI 0.93 to 1.14; 17 studies, 1988 women; moderate-quality evidence); or the risk of developing type 2 diabetes (metformin only) (RR 1.39, 95% CI 0.80 to 2.44; two studies, 754 women; moderate-quality evidence). The risk of undergoing induction of labour for those treated with insulin compared with oral anti-diabetic pharmacological therapy may possibly be increased, although the evidence was not clear (average RR 1.30, 95% CI 0.96 to 1.75; three studies, 348 women; I² = 32%; moderate-quality of evidence). There was no clear evidence of difference in postnatal weight retention between women treated with insulin and those treated with oral anti-diabetic pharmacological therapy (metformin) at six to eight weeks postpartum (MD -1.60 kg, 95% CI -6.34 to 3.14; one study, 167 women; low-quality evidence) or one year postpartum (MD -3.70, 95% CI -8.50 to 1.10; one study, 176 women; low-quality evidence). The outcomes of perineal trauma/tearing or postnatal depression were not reported in the included studies.For the infant, there was no evidence of a clear difference between those whose mothers had been treated with insulin and those treated with oral anti-diabetic pharmacological therapies for the risk of being born large-for-gestational age (average RR 1.01, 95% CI 0.76 to 1.35; 13 studies, 2352 infants; moderate-quality evidence); the risk of perinatal (fetal and neonatal death) mortality (RR 0.85; 95% CI 0.29 to 2.49; 10 studies, 1463 infants; low-quality evidence);, for the risk of death or serious morbidity composite (RR 1.03, 95% CI 0.84 to 1.26; two studies, 760 infants; moderate-quality evidence); the risk of neonatal hypoglycaemia (average RR 1.14, 95% CI 0.85 to 1.52; 24 studies, 3892 infants; low-quality evidence); neonatal adiposity at birth (% fat mass) (mean difference (MD) 1.6%, 95% CI -3.77 to 0.57; one study, 82 infants; moderate-quality evidence); neonatal adiposity at birth (skinfold sum/mm) (MD 0.8 mm, 95% CI -2.33 to 0.73; random-effects; one study, 82 infants; very low-quality evidence); or childhood adiposity (total percentage fat mass) (MD 0.5%; 95% CI -0.49 to 1.49; one study, 318 children; low-quality evidence). Low-quality evidence also found no clear differences between groups for rates of neurosensory disabilities in later childhood: hearing impairment (RR 0.31, 95% CI 0.01 to 7.49; one study, 93 children), visual impairment (RR 0.31, 95% CI 0.03 to 2.90; one study, 93 children), or any mild developmental delay (RR 1.07, 95% CI 0.33 to 3.44; one study, 93 children). Later infant mortality, and childhood diabetes were not reported as outcomes in the included studies.We also looked at comparisons for regular human insulin versus other insulin analogues, insulin versus diet/standard care, insulin versus exercise and comparisons of insulin regimens, however there was insufficient evidence to determine any differences for many of the key health outcomes. Please refer to the main results for more information about these comparisons.

AUTHORS' CONCLUSIONS

The main comparison in this review is insulin versus oral anti-diabetic pharmacological therapies. Insulin and oral anti-diabetic pharmacological therapies have similar effects on key health outcomes. The quality of the evidence ranged from very low to moderate, with downgrading decisions due to imprecision, risk of bias and inconsistency.For the other comparisons of this review (insulin compared with non-pharmacological interventions, different insulin analogies or different insulin regimens), there is insufficient volume of high-quality evidence to determine differences for key health outcomes.Long-term maternal and neonatal outcomes were poorly reported for all comparisons.The evidence suggests that there are minimal harms associated with the effects of treatment with either insulin or oral anti-diabetic pharmacological therapies. The choice to use one or the other may be down to physician or maternal preference, availability or severity of GDM. Further research is needed to explore optimal insulin regimens. Further research could aim to report data for standardised GDM outcomes.

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.

Feto-maternal outcomes and Glycemic control in Metformin versus insulin treated Gestational Diabetics

OBJECTIVE

To evaluate and compare feto-maternal outcomes and glycemic control in metformin versus insulin treated gestational diabetics.

METHODS

The study was conducted in 2010- 2012 as a part of M. Phil at Civil hospital, Lyari General Hospital and Mamji Hospital in Karachi. After written informed consent, 71 GDM diagnosed females with WHO criteria were enrolled. They were divided into two groups. Group-A, 32 females were given oral metformin 500 mg TDS while Group-B, 39 females were given insulin 0.8-0.9 mg/kg/day in two divided doses subcutaneously. Patients were followed till term. Feto-maternal outcomes were evaluated in 25 patients in each group who completed the study.

RESULTS

When groups were compared, newborns in Group-B were significantly more in weight (p=0.01). Significant numbers of babies were delivered after 38 weeks of pregnancy in Group-B (P=0.021). There were two intrauterine deaths and significantly higher HbA1C at term in Group-B. (P=0.03). FBS at term was non-significant (p=0.079) and there was more number of cesarean sections due to feto-maternal disproportion in Group-B (28% vs.2%). Results analyzed for glycemic control before and after the treatment revealed that FBS was statistically less in Group-A (p=0.00) whereas for Group-B the value of FBS and HbA1C was statistically high. (p=0.002 & 0.04 respectively).

CONCLUSION

Metformin has produced better effects on feto-maternal outcomes and glycemic control in comparison to Insulin in GDM.