Metformin safety in the management of gestational diabetes

Insulin Use During Gestational and Pre-existing Diabetes in Pregnancy: A Systematic Review of Study Design

INTRODUCTION

Insulin is the first-line pharmacologic therapy for women with diabetes in pregnancy. However, conducting well-designed randomized clinical trials (RCTs) and achieving recommended glycemic targets remains a challenge for this unique population. This systematic literature review (SLR) aimed to understand the evidence for insulin use in pregnancy and the outcome metrics most often used to characterize its effect on glycemic, maternal and fetal outcomes in gestational diabetes mellitus (GDM) and in pregnant women with diabetes.

METHODS

An SLR was conducted using electronic databases in Medline, EMBASE via Ovid platform, evidence-based medicine reviews (2010-2020) and conference proceedings (2018-2019). Studies were included if they assessed the effect of insulin treatment on glycemic, maternal or fetal outcomes in women with diabetes in pregnancy. Studies on any type of diabetes other than gestational or pre-existing diabetes as well as non-human studies were excluded.

RESULTS

In women diagnosed with GDM or pre-existing diabetes, most studies compared treatment of insulin with metformin (n = 35) followed by diet along with lifestyle intervention (n = 24) and glibenclamide (n = 12). Most studies reporting on glycemic outcomes compared insulin with metformin (n = 22) and glibenclamide (n = 4). Fasting blood glucose was the most reported clinical outcome of interest. Among the studies reporting maternal outcomes, method of delivery and delivery complications were most commonly reported. Large for gestational age, stillbirth and perinatal mortality were the most common fetal outcomes reported.

CONCLUSION

This SLR included a total of 108 clinical trials and observational studies with diverse populations and treatment arms. Outcomes varied across the studies, and a lack of consistent outcome measures to manage diabetes in pregnant women was observed. This elucidates a need for global consensus on study design and standardized clinical, maternal and fetal outcomes metrics.

Gestational Diabetes Mellitus and Preeclampsia: Correlation and Influencing Factors

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are common pregnancy complications with similar risk factors and pathophysiological changes. Evidence from previous studies suggests that the incidence of PE is significantly increased in women with GDM, but whether GDM is independently related to the occurrence of PE has remained controversial. GDM complicated by PE further increases perinatal adverse events with greater impact on the future maternal and offspring health. Identify factors associated with PE in women with GDM women, specifically those that are controllable, is important for improving pregnancy outcomes. This paper provides the findings of a review on the correlation between GDM and PE, factors associated with PE in women with GDM, possible mechanisms, and predictive markers. Most studies concluded that GDM is independently associated with PE in singleton pregnancy, and optimizing the treatment and management of GDM can reduce the incidence of PE, which is very helpful to improve pregnancy outcomes.

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.

Effects of metformin and insulin therapy regimens on postpartum oral glucose tolerance test results in pregnant women with gestational diabetes mellitus: a comparative study

OBJECTIVES

The main purpose of this study was to compare the effects of two regimens of metformin and insulin therapy on postpartum oral glucose tolerance test (OGTT) results in pregnant women with gestational diabetes mellitus (GDM).

METHODS

In this single-blind randomized clinical trial (RCT), a total number of 60 pregnant women meeting the inclusion criteria were assigned to two groups with a randomized block design (RBD): insulin therapy (IT) group (30 patients) and metformin therapy (MT) group (30 patients). At baseline, the data were comprised of prenatal maternal age, gestational age, GDM diagnosis, and maternal weight/height. During the postpartum period, 5-cc blood samples were taken from the pregnant women concerned to analyze their fasting blood sugar (FBS) levels. Then, the patients were asked to come back four days and six weeks later after delivery to check the OGTT results. At six weeks postpartum, in addition to OGTT, the glycated hemoglobin (HbA₁C) test was performed for all mothers. Finally, six weeks after delivery, these mothers were evaluated with regard to weight loss and body mass index (BMI).

RESULTS

Six weeks postpartum, the maternal weight and BMI significantly decreased in the MT group compared with the IT one, while there was no significant difference between both groups at baseline. On the fourth day, the OGTT results in the MT group were significantly lower in comparison with those in the IT group (p=0.012). At sixth weeks postpartum, the OGTT results were comparably lower in the MT group than those reported for the IT one; however, such a difference was not statistically significant (p=0.087).

CONCLUSIONS

According to the study results, metformin could be an effective and safe treatment for pregnant women suffering from GDM instead of insulin therapy.

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.

Efficacy of metformin in improving glycaemic control & perinatal outcome in gestational diabetes mellitus: A non-randomized study

BACKGROUND & OBJECTIVES

Gestational diabetes mellitus (GDM) can cause adverse perinatal outcome if not treated. Although insulin therapy has been the main treatment modality over decades but considering its cost and parenteral mode of administration, it does not seem to be appropriate, especially in low-resource settings. The objective of this study was to evaluate the role of metformin in GDM and know its efficacy as well as adverse effect on foetus and mother.

METHODS

All pregnant women with GDM who were not controlled on medical nutrition therapy and required metformin therapy were included in the study. Careful monitoring of blood sugar was done. Development of any maternal or foetal complications and adverse effect were recorded.

RESULTS

A total of 2797 pregnant women were screened, of whom 233 (8.3%) were found to have GDM. Of the 64 women with GDM (28.7%) who required metformin therapy, majority (93.8%) achieved blood sugar control, whereas three (4.7%) women failed. Caesarean section rate was 54 per cent, and 15.6 per cent neonates were large for gestational age. Only two (3.1%) women had gastrointestinal side effects which were minor and got resolved with time. No case of hypoglycaemia or perinatal mortality was reported.

INTERPRETATION & CONCLUSIONS

Our findings indicate that metformin may be used as a safe and effective oral hypoglycaemic agent in GDM, especially in low-resource settings where cost, storage and compliance are logistic issues. However, long-term follow up studies are needed to solve issues related to its safety in pregnancy.

Effects of metformin on pregnancy outcomes in women with polycystic ovary syndrome: A meta-analysis

AIM

The aim of the study is to evaluate the effects of metformin on pregnancy outcomes in women with polycystic ovary syndrome (PCOS).

METHODS

We searched electronic databases and bibliographies of relevant papers to identify studies comparing the pregnancy outcomes in the metformin group with those in the placebo or blank control group. Then, we did this meta-analysis based on the PRISMA guidelines. The primary outcomes included early pregnancy loss (EPL), preterm delivery, term delivery, and gestational diabetes mellitus (GDM). Secondary outcomes included pregnancy-induced hypertension (PIH), intrauterine growth restriction (IUGR), fetal malformation, vaginal delivery (VD), cesarean section (CS), and metformin's side effects, such as nausea or gastrointestinal discomfort. Certainly, data about neonatal death and macrosomia were analyzed if data available.

RESULTS

Finally, 13 studies including 5 randomized controlled trials (RCT) and 8 cohort studies involving 1606 pregnant women with PCOS were analyzed. The pooled OR of EPL was 0.19 with obvious statistical significance, manifesting that metformin help to lower the rate of EPL (95% CI 0.12-0.28, P < 0.00001). Simultaneously, metformin showed the advantage of reducing the prevalence of preterm delivery (OR 0.37, 95% CI 0.20-0.68, P = 0.002). In addition, metformin could promote term delivery greatly and the pooled OR was 5.23 with sharp statistical difference (95% CI 3.12-8.75, P < 0.00001).

CONCLUSION

Metformin treatment in women with PCOS throughout pregnancy could increase the possibility of term delivery, VD and reduce the risk of EPL, preterm labor, pregnancy complications such as GDM and PIH, with no serious side effects. Moreover, metformin was not teratogenic based on the limited data. So we may recommend metformin treatment for women with PCOS during the whole pregnancy period for it is quite beneficial and safe for both mothers and babies.

Gestational diabetes mellitus: challenges in diagnosis and management

Gestational diabetes mellitus (GDM) is a well-characterized disease affecting a significant population of pregnant women worldwide. It has been widely linked to undue weight gain associated with factors such as diet, obesity, family history, and ethnicity. Poorly controlled GDM results in maternal and fetal morbidity and mortality. Improved outcomes therefore rely on early diagnosis and tight glycaemic control. While straightforward protocols exist for screening and management of diabetes mellitus in the general population, management of GDM remains controversial with conflicting guidelines and treatment protocols. This review highlights the diagnostic and management options for GDM in light of recent advances in care.

Changing trends in management of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is on the rise globally. In view of the increasing prevalence of GDM and fetal and neonatal complications associated with it, there is a splurge of research in this field and management of GDM is undergoing a sea change. Trends are changing in prevention, screening, diagnosis, treatment and future follow up. There is emerging evidence regarding use of moderate exercise, probiotics and vitamin D in the prevention of GDM. Regarding treatment, newer insulin analogs like aspart, lispro and detemir are associated with better glycemic control than older insulins. Continuous glucose monitoring systems and continuous subcutaneous insulin systems may play a role in those who require higher doses of insulin for sugar control. Evidence exists that favors metformin as a safer alternative to insulin in view of good glycemic control and better perinatal outcomes. As the risk of developing GDM in subsequent pregnancies and also the risk of overt diabetes in later life is high, regular assessment of these women is required in future. Lifestyle interventions or metformin should be offered to women with a history of GDM who develop pre-diabetes. Further studies are required in the field of prevention of GDM for optimizing obstetric outcome.