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

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.

Cost-effectiveness analysis of metformin versus insulin in the treatment of gestational diabetes mellitus

OBJECTIVE

Although there have been many studies on gestational diabetes mellitus (GDM) treatment, there is still a knowledge gap regarding the comparative cost-effectiveness of metformin and insulin in the treatment phase. Existing studies have focused on treatment efficacy and drug safety, but relatively little has been explored regarding cost-effectiveness analysis. In particular, no comprehensive study has evaluated the cost-effectiveness of metformin and insulin for GDM treatment. Therefore, this study aimed to fill this knowledge gap by conducting a cost-effectiveness analysis of these two treatments for GDM.

METHODS

A decision-analytic model was used to compare the cost-effectiveness of metformin and insulin in China. Probabilities, costs, and utilities were derived from the literature. The cost and quality-adjusted life years (QALYs) were calculated using the roll-back method. The strategy was considered cost-effective if the incremental cost-effectiveness ratio (ICER) was below the willingness-to-pay (WTP) threshold of ¥242,938 per QALY. Sensitivity analyses were also conducted to assess the robustness of the results.

RESULTS

The roll-back analysis indicated that insulin was not cost-effective compared to metformin, resulting in increased costs and decreased QALYs, with a negative ICER. These findings suggested that metformin is a cost-effective option than insulin. Furthermore, the sensitivity analysis showed that the model was robust.

CONCLUSIONS

Compared with insulin, metformin is a cost-effective treatment option for GDM.

Therapeutic Potential of Thunbergia laurifolia L. Extract in Gestational Diabetes Mellitus: Insights from a Rat Model

OBJECTIVE

To assess the effects of Thunbergia laurifolia L. extract (TLE) on gestational diabetes mellitus (GDM) in a rat model.

METHODS

Thunbergia laurifolin L. leaves were subjected to ethanolic extraction. In vivo study, 50 pregnant rats were randomly divided into 5 groups (10 for each): non-GDM group, GDM induced by streptozotocin (STZ, 60 mg/kg i.p.), metformin (MET) 100 mg/kg, TLE 50, and 500 mg/kg groups. Administration was performed on gestation day 7 until term (day 21). The effects of TLE on blood glucose, insulin levels, lipid profiles, liver enzymes, and maternal performances were assessed. In in vitro study, the effect of TLE was examined using the organ bath for uterine force measurement.

RESULTS

In in vivo study, TLE significantly reduced blood glucose as compared to GDM (P<0.05) with gradually increased insulin level. This effect was consistent with islets of Langerhans restoration. Histologically, the uterine muscular layer displayed a marked increase in fiber area in response to both doses as compared to GDM (P<0.05). Additionally, TLE significantly reduced total cholesterol, triglyceride, and alanine transaminase levels (P<0.05). Intriguingly, TLE also led to a notable augmentation in gravid uterus size, live fetuses count, and implantation numbers, while significantly reducing the post-implantation loss rate associated with fetal classification (P<0.05). Thus, GDM improvements were close to those produced by MET. In in vitro study, TLE exerted a concentration-dependent inhibition of spontaneous uterine contractility (half-maximal inhibition concentration=1.2 mg/L). This inhibitory effect extended to potassium chloride depolarization and oxytocin-mediated contractions. When combined with its major constituent, rosmarinic acid, TLE produced an enhanced inhibitory effect (P<0.05).

CONCLUSIONS

TLE ameliorated blood glucose levels, enhanced uterine muscular structure, and improved maternal and fetal performance in GDM. TLE also displayed tocolytic properties. These findings underscore the need for further exploration of TLE as a potential tocolytic agent to mitigate GDM-associated complications.

Long-Term Impact on Offspring (5 to 11 Years of Age) of Metformin Use in Pregnancy in Mothers With Diabetes: A Systematic Review and Meta-Analysis

OBJECTIVE

Data are scant on the impact of metformin use in gestational diabetes mellitus/diabetes in pregnancy on long-term outcomes in children and mothers beyond 5 years of childbirth. This systematic review and meta-analysis aimed to evaluate the long-term impact of metformin use in pregnancy on children and their mothers.

METHODS

Electronic databases were searched for studies evaluating metformin compared with insulin for managing gestational diabetes mellitus/diabetes in pregnancy. The primary outcome was the change in body mass index (BMI) in children at the ages of 5 to 11 years. The secondary outcomes were alterations in other anthropometric measures, obesity, and changes in the levels of lipids and adipocytokines in children and mothers.

RESULTS

Children at the age of 9 years born to mothers who were treated with metformin during pregnancy had similar BMI (mean difference [MD], 1.09 kg/m2 [95% confidence interval {CI}, -0.44 to 2.62]; P = .16; I2 = 16%), waist circumference-to-height ratio (MD, 0.13 [95% CI, -0.05 to 0.30]; P = .16; I2 = 94%), dual-energy X-ray absorptiometry (DXA) total fat mass (MD, 0.68 kg [95% CI, -2.39 to 3.79]; P = .66; I2 = 70%), DXA total fat percent (MD, 0.04% [95% CI, -3.44 to 3.51]; P = .98; I2 = 56%), DXA total fat-free mass (MD, 0.81 kg [95% CI, -0.96 to 2.58]; P = .37; I2 = 55%), magnetic resonance imaging visceral adipose tissue volume (MD, 80.97 cm3 [95% CI, -136.47 to 298.41]; P = .47; I2 = 78%), and magnetic resonance spectroscopy liver fat percentage (MD, 0.27% [95% CI, -1.26 to 1.79]; P = .73; I2 = 0%) to those born to mothers who were treated with insulin. Serum adiponectin, leptin, alanine aminotransferase, and ferritin were comparable among groups. In children between the ages of 9 and 11 years, the occurrence of obesity, diabetes, or challenges in motor and social development were comparable between the 2 groups. After 9 years of childbirth, BMI and the risk of developing diabetes were similar between the 2 groups of women.

CONCLUSION

Metformin use in pregnancy did not show any adverse effects compared with insulin on long-term outcomes in children and their mothers.

Case report: Glycaemic management and pregnancy outcomes in a woman with an insulin receptor mutation, p.Met1180Lys

BACKGROUND

Heterozygous insulin receptor mutations (INSR) are associated with insulin resistance, hyperglycaemia and hyperinsulinaemic hypoglycaemia in addition to hyperandrogenism and oligomenorrhoea in women. Numerous autosomal dominant heterozygous mutations involving the INSR β-subunit tyrosine kinase domain resulting in type A insulin resistance have been previously described. We describe the phenotype, obstetric management and neonatal outcomes in a woman with type A insulin resistance caused by a mutation in the β-subunit of the INSR.

CASE PRESENTATION

We describe a woman with a p.Met1180Lys mutation who presents with hirsutism, oligomenorrhoea and diabetes at age 20. She has autoimmune thyroid disease, Coeliac disease and positive GAD antibodies. She is overweight with no features of acanthosis nigricans and is treated with metformin. She had 11 pregnancies treated with insulin monotherapy (n = 2) or combined metformin and insulin therapy (n = 9). The maximum insulin dose requirement was 134 units/day or 1.68 units/kg/day late in the second pregnancy. Mean birthweight was on the 37th centile in INSR positive offspring (n = 3) and the 94th centile in INSR negative offspring (n = 1).

CONCLUSION

The p.Met1180Lys mutation results in a phenotype of diabetes, hirsutism and oligomenorrhoea. This woman had co-existent autoimmune disease. Her insulin dose requirements during pregnancy were similar to doses observed in women with type 2 diabetes. Metformin may be used to improve insulin sensitivity in women with this mutation. Offspring inheriting the mutation tended to be smaller for gestational age.

Changes in Oxidative Stress and Intestinal Permeability during Pregnancy in Women with Gestational Diabetes Mellitus Treated with Metformin or Insulin and Healthy Controls: A Randomized Controlled Trial

Both oxidative stress and intestinal permeability are increased in hyperglycemic situations and have been shown to be reduced by metformin in type 2 diabetes mellitus (T2DM) patients. The aim of this study was to elucidate the effect of metformin on oxidative stress and intestinal permeability in women with gestational diabetes mellitus (GDM) treated with metformin compared to those treated with insulin and healthy controls. A total of 120 women were included from August 2016 to February 2022: 41 received metformin (MET group), 38 received insulin (INS group), and 41 were healthy controls. Baseline and antenatal visits were carried out at 25.4 ± 4.8 and 36.1 ± 0.8 weeks of pregnancy, respectively. Advanced oxidation protein products (AOPPs), total antioxidant capacity (TAC), and zonulin levels were measured at every visit. Zonulin levels from baseline to prepartum visit increased significantly in both healthy controls (0.6 ± 0.9 to 1.2 ± 1.7 ng/mL, p = 0.004) and the INS group (0.4 ± 0.3 to 0.6 ± 0.5 ng/mL, p = 0.034) but did not significantly change in the MET group (0.4 ± 0.4 to 0.5 ± 0.4 ng/mL, p = 0.202). However, TAC and AOPP levels significantly increased in women with GDM, both in the INS and MET groups but not in the healthy controls. In conclusion, in our population, metformin has been shown to avoid an increase in intestinal permeability but failed to avoid an increase in oxidative stress related to hyperglycemia.

Management of type 2 diabetes in pregnancy: a narrative review

The prevalence of type 2 diabetes (T2DM) at reproductive age is rising. Women with T2DM have a similarly high risk for pregnancy complications as pregnant women with type 1 diabetes. To reduce adverse pregnancy and neonatal outcomes, such as preeclampsia and preterm delivery, a multi-target approach is necessary. Tight glycemic control together with appropriate gestational weight gain, lifestyle measures, and if necessary, antihypertensive treatment and low-dose aspirin is advised. This narrative review discusses the latest evidence on preconception care, management of diabetes-related complications, lifestyle counselling, recommendations on gestational weight gain, pharmacologic treatment and early postpartum management of T2DM.

Systematic review of the use of metformin compared to insulin for the management of gestational diabetes: Implications for low-resource settings

Introduction

This systematic review examines the effectiveness of metformin treatment compared to insulin treatment for gestational diabetes within the context of a low-resource environment.

Methods

Electronic data searches of Medline, EMBASE, Scopus and Google scholar databases from 1 January, 2005 to 30 June, 2021 were performed using medical subject headings: 'gestational diabetes or pregnancy diabetes mellitus' AND 'Pregnancy or pregnancy outcomes' AND 'Insulin' AND 'Metformin Hydrochloride Drug Combination/or Metformin/or Hypoglycemic Agents' AND 'Glycemic control or blood glucose'. Randomized controlled trials were included if: participants were pregnant women with gestational diabetes mellitus (GDM); the interventions were metformin and/or insulin. Studies among women with pre-gestational diabetes, non-randomised control trials or studies with a limited description of the methodology were excluded. Outcomes included adverse maternal outcomes: weight gain, C-section, pre-eclampsia and glycaemic control and adverse neonatal outcomes: birth weight, macrosomia, pre-term birth and neonatal hypoglycaemia. The revised Cochrane Risk of Bias Assessment for randomised trials was used for the evaluation of bias.

Results

We screened 164 abstracts and 36 full-text articles. Fourteen studies met the inclusion criteria. The studies provide moderate to high-quality evidence demonstrating the effectiveness of metformin as an alternative therapy to insulin. Risk of bias was low; multiple countries and robust sample sizes improved external validity. All studies were from urban centres with no rural data.

Conclusion

These recent high quality studies comparing metformin to insulin for the treatment of GDM generally found either improved or equivalent pregnancy outcome and good glycaemic control for most patients, although many required insulin supplementation. Its ease of use, safety and efficacy suggest metformin may simplify the management of gestational diabetes, particularly in rural and other low-resource environments.

Medications for Managing Preexisting and Gestational Diabetes in Pregnancy

Persons with gestational and pregestational diabetes during pregnancy may require pharmacologic agents to achieve pregnancy glycemic targets, and the available medications for use in pregnancy are limited. Insulin is the only FDA-approved medication for use in pregnancy and has the greatest evidence for safety and efficacy. Metformin and glyburide are the most commonly used oral agents in pregnancy. Understanding each medication's unique pharmacokinetics, potential side effects, fetal or childhood risks, gestational age of medication initiation and patient's diabetes care barriers are important aspects of shared decision-making and choosing a regimen that will achieve glycemic and pregnancy goals.

[Gestational diabetes mellitus (Update 2023)]

Gestational diabetes (GDM) is defined as any degree of glucose intolerance with onset during pregnancy and is associated with increased feto-maternal morbidity as well as long-term complications in mothers and the offspring. Women detected to have diabetes early in pregnancy receive the diagnosis of overt, non-gestational, diabetes (glucose: fasting ≥ 126 mg/dl, spontaneous ≥ 200 mg/dl or HbA_1c ≥ 6.5% before 20 weeks of gestation). GDM is diagnosed by an oral glucose tolerance test (oGTT) or increased fasting glucose (≥ 92 mg/dl). Screening for undiagnosed type 2 diabetes at the first prenatal visit is recommended in women at increased risk (history of GDM/pre-diabetes; malformation, stillbirth, successive abortions or birth weight > 4500 g previously; obesity, metabolic syndrome, age > 35 years, vascular disease; clinical symptoms of diabetes (e.g. glucosuria) or ethnic origin with increased risk for GDM/T2DM (Arab, South- and Southeast Asian, Latin American)) using standard diagnostic criteria. Performance of the oGTT (120 min; 75 g glucose) may already be indicated in the first trimester in high-risk women but is mandatory between gestational week 24-28 in all pregnant women with previous non-pathological glucose metabolism. Following WHO recommendations, which are based on the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study, GDM is defined, if fasting venous plasma glucose is ≥ 92 mg/dl or 1 h ≥ 180 mg/dl or 2 h ≥ 153 mg/dl after glucose loading (international consensus criteria). In case of one pathological value a strict metabolic control is mandatory. After bariatric surgery we do not recommend to perform an oGTT due to risk of postprandial hypoglycemia. All women with GDM should receive nutritional counseling, be instructed in blood glucose self-monitoring and motivated to increase physical activity to moderate intensity levels-if not contraindicated (Evidence level A). If blood glucose levels cannot be maintained in the therapeutic range (fasting < 95 mg/dl and 1 h after meals < 140 mg/dl, Evidence level B) insulin therapy should be initiated as first choice (Evidence level A). Maternal and fetal monitoring is required in order to minimize maternal and fetal/neonatal morbidity and perinatal mortality. Regular obstetric examinations including ultrasound examinations are recommended (Evidence level A). Neonatal care of GDM offspring at high risk for hypoglycaemia includes blood glucose measurements after birth and if necessary appropriate intervention. Monitoring the development of the children and recommendation of healthy lifestyle are important issues to be tackled for the whole family. After delivery all women with GDM have to be reevaluated as to their glucose tolerance by a 75 g oGTT (WHO criteria) 4-12 weeks postpartum. Assessment of glucose parameters (fasting glucose, random glucose, HbA_1c or optimally oGTT) are recommended every 2-3 years in case of normal glucose tolerance. All women have to be instructed about their increased risk of type 2 diabetes and cardiovascular disease at follow-up. Possible preventive meassures, in particular lifestyle changes as weight management and maintenance/increase of physical activity should be discussed (evidence level A).

Metformin: Sex/Gender Differences in Its Uses and Effects—Narrative Review

Metformin (MTF) occupies a major and fundamental position in the therapeutic management of type 2 diabetes mellitus (T2DM). Gender differences in some effects and actions of MTF have been reported. Women are usually prescribed lower MTF doses compared to men and report more gastrointestinal side effects. The incidence of cardiovascular events in women on MTF has been found to be lower to that of men on MTF. Despite some promising results with MTF regarding pregnancy rates in women with PCOS, the management of gestational diabetes, cancer prevention or adjunctive cancer treatment and COVID-19, most robust meta-analyses have yet to confirm such beneficial effects.

Current Therapeutic Use of Metformin During Pregnancy: Maternal Changes, Postnatal Effects and Safety

Metformin is one of the most easily available medications for diabetes and has a relatively low cost. It is not only used in diabetes but is also effective in polycystic ovarian syndrome (PCOS) and obesity. Although insulin is the first choice when it comes to treating pregnant women with gestational diabetes mellitus (GDM), metformin has also been debated as a good choice after modification of diet. As metformin passes through the placenta, it is essential to know its consequence of leading to insulin resistance in the fetus as well as the impact on postnatal development. The use of metformin during GDM has raised many trials demonstrating that outcomes from the use of metformin are similar to those achieved with insulin. Follow-up studies were also conducted that assessed the impact on children exposed to metformin in utero. This review highlights the experimental evidence relating to the use of metformin during pregnancy for different conditions, and its impact on the growth and development of offspring.