Fasting blood glucose predicts response to extended-release metformin in gestational diabetes mellitus

The Use of Non-insulin Agents in Gestational Diabetes: Clinical Considerations in Tailoring Therapy

PURPOSE OF REVIEW

To assess evidence to date for use of non-insulin agents in treatment of gestational diabetes mellitus.

RECENT FINDINGS

There has been increasing interest in the use of non-insulin agents, primarily metformin and glyburide (which both cross the placenta). Metformin has been associated with less maternal weight gain; however, recent studies have shown a trend toward increased weight in offspring exposed to metformin in utero. Glyburide has been associated with increased neonatal hypoglycemia. Glycemic control during pregnancy is essential to optimize both maternal and fetal outcomes. There are a myriad of factors to consider when designing treatment programs including patient preference, phenotype, and glucose patterns. While insulin is typically recommended as first-line, some women refuse or cannot afford insulin and in those cases, non-insulin agents may be used. Further studies are needed to assess treatment in pregnancy, perinatal outcomes, and particularly long-term metabolic profiles in mothers and offspring.

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.

Predictors of metformin failure in gestational diabetes mellitus (GDM)

INTRODUCTION AND OBJECTIVE

The role of metformin in gestational diabetes mellitus (GDM) is also increasing. However, almost half of metformin-treated women required additional insulin. Therefore, identifying the characteristics of these women may help define optimal therapeutic strategy.

METHODS

This is a retrospective cohort study done in a District General Hospital, UK. GDM was diagnosed by 75 g OGTT test between 24 and 28 weeks of gestation with fasting levels of ≥6.1 mmol/l and/or 2 h postprandial (PP) level of ≥7.8 mmol/l. Logistic regression and receiver operator curves (ROC) were performed to identify the predictors of metformin failure.

RESULTS

Out of 228 women with GDM included, 46/228 (20.2%) and 151/228 (66.2%) received insulin and metformin as first-line medication respectively. Among the metformin-treated, 13 stopped treatment and were excluded from analysis. Of the included 138 metformin-treated women, 77 (55.8%) required supplementary insulin (metformin failure). Metformin failure group had higher maternal age and fasting glucose level at OGTT, HbA1c at OGTT and earlier gestational age (GA) at medication initiation. Metformin failure was predicted if fasting OGTT level >4.8 mmol/l (69% sensitivity and 62% specificity). If the fasting levels of IADPSG (International Association of Diabetes and Pregnancy Study Groups) criteria and NICE (National Institute of Health and Care Excellence) were used, the positive predictive value was 78% and 77% respectively.

CONCLUSION

As women with higher fasting glucose levels have higher chance of necessitating insulin in later pregnancies, appropriate addition of insulin at metformin initiation for these women could help better glycaemic control throughout pregnancy.

Outcomes for Women with Gestational Diabetes Treated with Metformin: A Retrospective, Case-Control Study

Metformin is increasingly being used a therapeutic option for the management of gestational diabetes mellitus (GDM). The aim of this study was to compare the maternal characteristics and perinatal outcomes of women with GDM treated with metformin (with or without supplemental insulin) with those receiving other management approaches. A retrospective, case-control study was carried out and 83 women taking metformin were matched 1:1 with women receiving insulin or diet and lifestyle modification alone. Women managed with diet and lifestyle modification had a significantly lower fasting plasma glucose (p < 0.001) and HbA1c (p < 0.01) at diagnosis of GDM. Furthermore, women managed with metformin had a higher early pregnancy body mass index (BMI) compared to those receiving insulin or diet and lifestyle modification (p < 0.001). There was no difference in mode of delivery, birth weight or incidence of large- or small-for-gestational-age neonates between groups. Women receiving glucose lowering therapies had a higher rate of neonatal hypoglycaemia (p < 0.05). The incidence of other adverse perinatal outcomes was similar between groups. Despite their greater BMI, women with metformin-treated GDM did not have an increased risk of adverse perinatal outcomes. Metformin is a useful alternative to insulin in the management of GDM.

Use of metformin earlier in pregnancy predicts supplemental insulin therapy in women with gestational diabetes

The use of metformin in gestational diabetes is safe and effective, yet some women require additional insulin therapy to achieve glycaemic targets. We found a significant association between earlier gestational age at initiation of metformin therapy and the necessity for supplemental insulin in women treated with metformin during pregnancy.

Identification of metformin poor responders, requiring supplemental insulin, during randomization of metformin versus insulin for the control of gestational diabetes mellitus

AIM

To evaluate glycemic control among women with gestational diabetes mellitus (GDM) under insulin versus metformin (with or without insulin supplementation), and to identify metformin poor responders requiring supplemental insulin.

METHODS

In Ain Shams University Hospital, mothers with 26-32-week GDM pregnancies, failing diet control, were randomized to receive metformin (n = 47) or insulin (n = 48). The primary outcome was glycemic control. Secondary outcomes included maternal weight, parameters predicting successful metformin monotherapy, neonatal hypoglycemia, and birthweight.

RESULTS

Women using metformin (23.4% needing supplemental insulin) gained less weight (P < 0.001), and had lower fasting glucose during the first and last 2 weeks of treatment (P = 0.014 and 0.008, respectively) when compared with insulin monotherapy. Insulin supplementation in the metformin group was related to initial body mass index, HbA1c, oral glucose tolerance test (GTT), and first week mean glucose level. The 1-h glucose level during initial GTT (Hr1-GTT) and the mean fasting glucose level during the first week of therapy (Wk1-mFG) were the two independent parameters associated with requiring supplemental insulin. Women with Hr1-GTT >212 mg/dL and Wk1-mFG >95 mg/dL had a risk ratio of 58.6 (95%CI: 3.68-933.35, P = 0.004) and 11.5 (95%CI: 2.77-47.34,= 0.0008), respectively for needing supplemental insulin during the course of the study compared with women without.

CONCLUSION

Metformin is an effective and safe alternative to insulin in GDM. Women using metformin (± supplemental insulin) had similar glycemic control, less weight gain, and similar rates of side-effects as those on insulin monotherapy. Insulin supplementation to metformin therapy was more likely with elevated Hr1-GTT and Wk1-mFG.

The Role of Metformin in Metabolic Disturbances during Pregnancy: Polycystic Ovary Syndrome and Gestational Diabetes Mellitus

Maintenance of gestation implicates complex function of multiple endocrine mechanisms, and disruptions of the global metabolic environment prompt profound consequences on fetomaternal well-being during pregnancy and postpartum. Polycystic Ovary Syndrome (PCOS) and gestational diabetes mellitus (GDM) are very frequent conditions which increase risk for pregnancy complications, including early pregnancy loss, pregnancy-induced hypertensive disorders, and preterm labor, among many others. Insulin resistance (IR) plays a pivotal role in the pathogenesis of both PCOS and GDM, representing an important therapeutic target, with metformin being the most widely prescribed insulin-sensitizing antidiabetic drug. Although traditional views neglect use of oral antidiabetic agents during pregnancy, increasing evidence of safety during gestation has led to metformin now being recognized as a valuable tool in prevention of IR-related pregnancy complications and management of GDM. Metformin has been demonstrated to reduce rates of early pregnancy loss and onset of GDM in women with PCOS, and it appears to offer better metabolic control than insulin and other oral antidiabetic drugs during pregnancy. This review aims to summarize key aspects of current evidence concerning molecular and epidemiological knowledge on metformin use during pregnancy in the setting of PCOS and GDM.

Metformin combined with mirtazapine for treatment of anorexia nervosa with dyspepsia: Clinical effect and impact on serum levels of norepinephrine, 5-hydroxy tryptamine and dopamine

AIM: To explore the clinical effect of metformin combined with mirtazapine in the treatment of anorexia nervosa (AN) with dyspepsia.

METHODS: One hundred AN patients with dyspepsia treated at our hospital were randomly divided into either an observation group or a control group (n = 50 for each group). The control group was treated with mirtazapine tablets, and the observation group was additionally given oral metformin on the basis of mirtazapine tablets. Gastric juice pH was compared between before and after treatment and between the two groups. After 2, 6, and 12 wk of treatment, body weight changes, Hamilton depression scale (HAMD) score, and Hamilton anxiety scale (HAMA) score were compared between the two groups. Serum norepinephrine (NE), 5-hydroxy tryptamine (5-HT), dopamine (DA) and blood glucose levels were also compared.

RESULTS: Gastric juice pH increased significantly after treatment in both groups, and the increase was more significant in the observation group (t = 5.658, P < 0.05). After 2, 6, and 12 wk of treatment, body weight significantly increased in both groups compared with before treatment. After 6 and 12 wk of treatment, body weight was significantly lower in the observation group than in the control group (t = 4.805, 4.864, P < 0.05). After treatment, HAMA and HAMD scores decreased significantly, serum NE, 5-HT and DA levels significantly increased in both groups compared with before treatment (t = 3.784, 4.315, 4.783, P < 0.05). After treatment, fasting plasma glucose (FPG), glycated haemoglobin (HbAlc), and 2-h plasma glucose (2 h PG) tended to decrease in the observation group compared with before treatment and the control group, but the differences were not statistically significant (P > 0.05). TESS score and the incidence of adverse reactions showed no significant differences between the two groups (P > 0.05).

CONCLUSION: Metformin combined with mirtazapine can improve depressive symptoms and appetite in the treatment of AN, without obvious weight gain or hypoglycemia symptoms.

First-trimester exposure to metformin and risk of birth defects: a systematic review and meta-analysis

BACKGROUND

Metformin is generally considered a non-teratogenic drug; however, only a few studies specifically designed to assess the rate of congenital anomalies after metformin use have been published in the literature. The objects of the present study were to review all of the prospective and retrospective studies reporting on women treated with metformin at least during the first trimester of their pregnancy and to estimate the overall rate of major birth defects.

METHODS

Databases were searched for English language articles until December 2013. Inclusion criteria for the meta-analysis were: a case group of women with PCOS or pre-pregnancy type 2 diabetes and first-trimester exposure to metformin; a disease-matched control group which was not exposed to metformin or other oral anti-diabetic agents; and a list of the major anomalies in both the study and the control groups. A random effects model was used for the meta-analysis of data, using odds ratios. Studies not fulfilling the inclusion criteria for the meta-analysis but reporting relevant data on major malformations in women diagnosed with PCOS were then used to estimate the overall birth defects rate.

RESULTS

Meta-analysis of nine controlled studies with women affected by PCOS detected that the rate of major birth defects in the metformin-exposed group was not statistically increased compared with the disease-matched control group and that there was no significant heterogeneity among the studies. The metformin-exposed sample was composed of 351 pregnancies and the OR of major birth defects was 0.86 (95% confidence interval: 0.18-4.08; Pheterogeneity = 0.71). By evaluating all of the non-overlapping PCOS studies reported in the literature, even those without an appropriate control group, the overall rate of major anomalies was 0.6% in the sample of 517 women who discontinued the therapy upon conception or confirmation of pregnancy and 0.5% in the sample of 634 women who were treated with metformin throughout the first trimester of their pregnancy. Regarding type 2 diabetic women, we did not identify a sufficient number of studies with metformin exposure during the first trimester to proceed with the meta-analysis.

CONCLUSIONS

There is currently no evidence that metformin is associated with an increased risk of major birth defects in women affected by PCOS and treated during the first trimester. However larger ad hoc studies are warranted in order to definitely confirm the safety and efficacy of this drug in pregnancy.