Glyburide for the treatment of gestational diabetes. A critical appraisal

Lack of uniformity in screening, diagnosis and management of gestational diabetes mellitus among health practitioners across major cities of Pakistan

OBJECTIVE

To determine knowledge, attitude and practice (KAP) regarding management of Gestational Diabetes Mellitus (GDM) among Health Care Providers in major cities of Pakistan.

METHODS

A knowledge, attitude and practice (KAP) questionnaire based study was conducted in major cities in Pakistan from health care providers in public and private hospitals and clinics. Questionnaires were provided to the health care providers regarding screening, diagnosis and management of patients with GDM. Data analysis was done using IBM SPSS 20.

RESULTS

A total of 210 doctors took part in the study. 55 (26%) reported using fasting blood glucose as screening test for GDM whereas 129(61.4%) respondents used Oral Glucose Tolerance based WHO criteria for diagnosing GDM. Thirty six (17%) and 98(46.7%) doctors referred their patients to Gynecologists. For treating GDM, 64(30.5%) doctors prescribed insulin (NPH/Regular, 70/30 Mix). 112 (53.5) doctors used combination of capillary glucose by glucometer and plasma blood glucose tests for monitoring of glycemic control of patients with GDM.

CONCLUSION

There is lack of agreed screening tests and criteria for diagnosis and management of GDM patients. Doctors need to be educated to follow evidence based diagnostic and management guidelines so that GDM patients can be effectively managed. Recently released South Asian Federation Societies and Pakistan Endocrine Society guidelines could be much needed consensus guidelines for doctors to apply in their daily practice to improve GDM diagnosis and treatment.

Metformin use in pregnancy: promises and uncertainties

Metformin has been prescribed in pregnancy for over 40 years; for much of this time, use has been limited both in numbers and geographically, and the evidence base has been confined to observational studies. In early years, perceived safety concerns and lack of availability of the drug in many countries acted as a barrier to use. More recently, RCTs have begun to examine the role of metformin in pregnancy in much-needed detail. However, this evidence base has been interpreted differently in different countries, leading to very wide variation in its current application in pregnancy. In this short review, we will discuss the history of metformin in pregnancy and highlight some of the key clinical trials. We will then consider some of the remaining controversies associated with metformin use in pregnancy, most important of these being the potential for long-term 'programming' effects on the fetus as a result of metformin being able to cross the placenta. We will also consider clinical situations where metformin might be avoided. Finally, we will discuss some future directions for this drug as it reaches its sixtieth anniversary.

Gestational diabetes mellitus-right person, right treatment, right time?

BACKGROUND

Personalised treatment that is uniquely tailored to an individual's phenotype has become a key goal of clinical and pharmaceutical development across many, particularly chronic, diseases. For type 2 diabetes, the importance of the underlying clinical heterogeneity of the condition is emphasised and a range of treatments are now available, with personalised approaches being developed. While a close connection between risk factors for type 2 diabetes and gestational diabetes has long been acknowledged, stratification of screening, treatment and obstetric intervention remains in its infancy.

CONCLUSIONS

Although there have been major advances in our understanding of glucose tolerance in pregnancy and of the benefits of treatment of gestational diabetes, we argue that far more vigorous approaches are needed to enable development of companion diagnostics, and to ensure the efficacious and safe use of novel therapeutic agents and strategies to improve outcomes in this common condition.

Safety considerations with pharmacological treatment of gestational diabetes mellitus

The number of women with gestational diabetes mellitus (GDM: diabetes first diagnosed in pregnancy) continues to grow, as do the associated risks of antenatal and postnatal complications and the chance of future diabetes and obesity in both mother and offspring. Recent randomised controlled trials have demonstrated clear benefits for intensive management of GDM using lifestyle modification, self blood glucose monitoring, close clinical supervision and, where glycaemia remains inadequately controlled, insulin therapy. More recently, metformin and glibenclamide have been shown to adequately reduce hyperglycaemia as part of a stepped approach to GDM management, with a switch to insulin therapy where necessary. Other oral medications have not been shown to be safe in pregnancy. Human insulin therapy is safe within the limits of hypoglycaemia and weight gain. Most insulin analogues are also now considered safe for use in pregnancy (insulin lispro, aspart and detemir). Metformin therapy is oral, and therefore preferred to insulin, but is associated with more gastrointestinal adverse effects, although not hypoglycaemia or weight gain. Conversely, glibenclamide is also an oral therapy but is associated with hypoglycaemia and weight gain. However, metformin crosses the placenta and it remains unclear whether glibenclamide crosses the placenta or not: long-term risks have not been shown, and are thought to be minimal, but further studies are needed. Metformin is seen by some as the treatment of choice where weight gain is an issue, providing that the unanswered questions over the long-term safety of oral agents have been discussed.

Oral antidiabetic agents in gestational diabetes: a narrative review of current evidence

Gestational diabetes mellitus (GDM) classically occurs when maternal glucose metabolism is unable to compensate the progressive development of insulin resistance that arises from the continuously rising diabetogenic placental hormones. Although most women can be treated satisfactorily with diet alone, some require more intensive treatment. Insulin has been the most reliable treatment strategy in GDM over several decades. Although a long time has passed since the publication of two randomized controlled trials suggesting comparable efficacy and safety of metformin and glibenclamide, international bodies have not yet approved these oral agents. However, with the consistently emerging efficacy and safety data of these two drugs in the past decade, they may perhaps open a rather new door. The aim of this narrative review is to critically evaluate the existing evidence regarding safety and efficacy of oral drugs in GDM accumulated since the first publication in year 2000, suggesting clinical equivalency of glibenclamide (glyburide).

The use of oral hypoglycaemic agents in pregnancy

While insulin has been the treatment of choice when lifestyle measures do not maintain glycaemic control during pregnancy, recent studies have suggested that certain oral hypoglycaemic agents may be safe and acceptable alternatives. With the exception of metformin and glibenclamide (glyburide), there are insufficient data to recommend treatment with any other oral hypoglycaemic agent during pregnancy. There are no serious safety concerns with metformin, despite it crossing the placenta. When used in the first trimester, there is no increase in congenital abnormalities and there appears to be a reduction in miscarriage, pre-eclampsia and subsequent gestational diabetes. Studies of the use of metformin in gestational diabetes show at least equivalent neonatal outcomes, while reporting reductions in neonatal hypoglycaemia, maternal hypoglycaemia and weight gain and improved treatment satisfaction. Glibenclamide effectively lowers blood glucose in women with gestational diabetes, possibly with a lower treatment failure rate than metformin. Although generally well tolerated, some studies have reported higher rates of pre-eclampsia, neonatal jaundice, longer stay in the neonatal care unit, macrosomia and neonatal hypoglycaemia. There is a paucity of long-term follow-up data on children exposed to oral agents in utero. The American College of Obstetrics and Gynecology and the UK National Institute of Health and Care Excellence (NICE) have recommended that either metformin or glibenclamide can be used to treat gestational diabetes. Metformin is also recommended for use in the pre-conception period by NICE. By contrast, the American Diabetes Association recommends that both drugs should only be used during pregnancy in the context of clinical trials.

Management of diabetes in pregnancy

The link between diabetes and poor pregnancy outcomes is well established. As in the non-pregnant population, pregnant women with diabetes can experience profound effects on multiple maternal organ systems. In the fetus, morbidities arising from exposure to diabetes in utero include not only increased congenital anomalies, fetal overgrowth, and stillbirth, but metabolic abnormalities that appear to carry on into early life, adolescence, and beyond. This article emphasizes the newest guidelines for diabetes screening in pregnancy while reviewing their potential impact on maternal and neonatal complications that arise in the setting of hyperglycemia in pregnancy.

Diabetes gestacional: um algoritmo de tratamento multidisciplinar

O tratamento do diabetes gestacional é importante para evitar a morbimortalidade materno-fetal. O objetivo deste artigo é descrever o tratamento atualmente disponível para o manejo otimizado da hiperglicemia na gestação e sugerir um algoritmo de tratamento multidisciplinar. A terapia nutricional é a primeira opção de tratamento para as gestantes, e a prática de exercício físico leve a moderado deve ser estimulada na ausência de contraindicações obstétricas. O tratamento medicamentoso está recomendado quando os alvos glicêmicos não são atingidos ou na presença de crescimento fetal excessivo à ultrassonografia. O tratamento tradicional do diabetes gestacional é a insulinoterapia, embora mais recentemente a metformina venha sendo considerada uma opção segura e eficaz. A monitorização do tratamento é realizada com aferição da glicemia capilar e com avaliação da circunferência abdominal fetal por meio de ultrassonografia obstétrica a partir da 28ª semana de gestação.

Treatment of gestational diabetes mellitus: glyburide compared to subcutaneous insulin therapy and associated perinatal outcomes

OBJECTIVE

To examine perinatal outcomes in women with gestational diabetes mellitus treated with glyburide compared to insulin injections.

STUDY DESIGN

This is a retrospective cohort study of women diagnosed with gestational diabetes mellitus (GDM) who required pharmaceutical therapy and were enrolled in the Sweet Success California Diabetes and Pregnancy Program between 2001 and 2004, a California state-wide program. Women managed with glyburide were compared to women treated with insulin injections. Perinatal outcomes were compared using chi-square test and multivariable logistic regression models; statistical significance was indicated by p < 0.05 and 95% confidence intervals (CI).

RESULTS

Among the 10,682 women with GDM who required medical therapy and met study criteria, 2073 (19.4%) received glyburide and 8609 (80.6%) received subcutaneous insulin injections. Compared to insulin therapy and controlling for confounders, oral hypoglycemic treatment was associated with increased risk of birthweight >4000 g (aOR = 1.29; 95% CI [1.03-1.64]), and admission to the intensive care nursery (aOR = 1.46 [1.07-2.00]).

CONCLUSION

Neonates born to women with gestational diabetes managed on glyburide, and were more likely to be macrosomic and to be admitted to the intensive care unit compared to those treated with insulin injections. These findings should be examined in a large, prospective trial.

Contributions of human cytochrome P450 enzymes to glyburide metabolism

Glyburide (GLB) is a widely used oral sulfonylurea for the treatment of gestational diabetes. The therapeutic use of GLB is often complicated by a substantial inter-individual variability in the pharmacokinetics and pharmacodynamics of the drug in human populations, which might be caused by inter-individual variations in factors such as GLB metabolism. Therefore, there has been a continued interest in identifying human cytochrome P450 (CYP) isoforms that play a major role in the metabolism of GLB. However, contrasting data are available in the present literature in this regard. The present study systematically investigated the contributions of various human CYP isoforms (CYP3A4, CYP3A5, CYP2C8, CYP2C9 and CYP2C19) to in vitro metabolism of GLB. GLB depletion and metabolite formation in human liver microsomes were most significantly inhibited by the CYP3A inhibitor ketoconazole compared with the inhibitors of other CYP isoforms. Furthermore, multiple correlation analysis between GLB depletion and individual CYP activities was performed, demonstrating a significant correlation between GLB depletion and the CYP3A probe activity in 16 individual human liver microsomal preparations, but not between GLB depletion and the CYP2C19, CYP2C8 or CYP2C9 probe activity. By using recombinant supersomes overexpressing individual human CYP isoforms, it was found that GLB could be depleted by all the enzymes tested; however, the intrinsic clearance (V(max)/K(m)) of CYP3A4 for GLB depletion was 4-17 times greater than that of other CYP isoforms. These results confirm that human CYP3A4 is the major enzyme involved in the in vitro metabolism of GLB.

Hypoglycemics: pharmacokinetic considerations during pregnancy

A wide range of physiological and hormonal changes occur during pregnancy. Most begin early in the first trimester and increase by the last trimester. These changes can significantly affect pharmacokinetics and pharmacodynamics of drugs and thus may alter their safety and efficacy. Approximately 5% of pregnant women are affected by some form of diabetes, with gestational diabetes being the most prevalent. Several classes of antidiabetic drugs are currently available for the treatment of diabetes, including human insulin, its short and long analogues, and oral hypoglycemic agents. Maternal and fetal responses to these drugs can be affected by changes in absorption, distribution, and elimination in both the mother and the placental-fetal unit. This can dictate the amount of drug that can cross and the amount that is metabolized or eliminated by the placenta. Further studies are needed on the safety of antidiabetic drugs in pregnancy to clarify the extent of their transplacental passage. Specifically, in vitro placental perfusion studies in combination with controlled trials and cord blood measurements can provide insight in to the pharmacokinetics of drug transport across the placenta. This article reviews common types of antidiabetic drugs, focusing on pharmacokinetic considerations that need to be incorporated into the decision on treatment in pregnancy.

Can Pregnant Diabetics be Treated with Glyburide?

Until the last decade, oral hypoglycemic agents have not been recommended in pregnancy owing to fear of their potential adverse fetal effects, including teratogenicity and neonatal hypoglycemia. However, the evidence in support of these recommendations is weak and is principally based on case series involving the use of first-generation sulfonylureas. Studies using a single-cotyledon placental model have found glyburide to only minimally cross the placenta, an observation that paved the way for a landmark randomized clinical trial that found glyburide to be as safe and effective as insulin in the management of gestational diabetes mellitus. Still, contradicting results regarding its trans-placental transfer, lack of adequate data regarding its safety during the first trimester and reports of increased neonatal morbidity raise concerns regarding the universal application of glyburide as an alternative to insulin therapy in diabetic pregnant women. Thus, there is a need for large, randomized, controlled trials with adequate power to evaluate the possibility of increased neonatal metabolic complications as well as the long-term outcome of infants born to mothers treated with glyburide and insulin. Unless future studies refute current data regarding the efficacy and safety of glyburide, we believe that, owing to its ease of administration, convenience and low cost, glyburide will become the first line of medical treatment in patients with gestational diabetes mellitus within the next few years.

Gestational diabetes: the need for a common ground

Gestational diabetes mellitus is a substantial and growing health concern in many parts of the world. Certain populations are especially vulnerable to developing this condition because of genetic, social, and environmental factors. Gestational diabetes has serious, long-term consequences for both baby and mother, including a predisposition to obesity, metabolic syndrome, and diabetes later in life. Early detection and intervention can greatly improve outcomes for women with this condition and their babies. Unfortunately, screening and diagnostic tests are not uniform worldwide, which could lead not only to underdiagnosis but also undermanagement of the illness. Here, we report the controversies surrounding the causes, screening, diagnosis, management, and prevention of gestational diabetes, and give specific recommendations for research studies to address the major issues of this medical condition.

Is fasting glucose level during oral glucose tolerance test an indicator of the insulin need in gestational diabetes?

Maintenance of a good metabolic control improves foetal and maternal outcomes in gestational diabetes mellitus (GDM). The aim of this study is to investigate the utility of diagnostic oral glucose tolerance test (OGTT) in prediction of the need of insulin in patients with GDM. One hundred and fifty five consecutive patients with GDM were included in the study. Patients were ordered MNT first. Those who failed to maintain glycemic targets were treated with insulin. Glucose levels obtained from the diagnostic OGTT were evaluated regarding the need of insulin during the rest of pregnancy. Fasting, 1h and 3h post-load glucose levels were significantly elevated in patients who required insulin. Multivariate analysis showed that fasting glucose level on OGTT was an independent predictor for the insulin need. A cut-off value of 105mg/dl had a fair specificity (91.89%) and positive predictive value (80.64%) for the prediction of patients who required insulin during the rest of their pregnancy. Our results suggest that fasting glucose level on OGTT is a predictor of the need for insulin treatment in GDM. A cut-off level of 105mg/dl seems to effectively determine high-risk patients for additional treatment other than MNT in GDM.