Improving the care of women with gestational diabetes

Organic Cation Transporter 3 Facilitates Fetal Exposure to Metformin during Pregnancy

Metformin, an oral antihyperglycemic, is increasingly being prescribed to pregnant women with gestational diabetes. Metformin is a hydrophilic cation and relies on organic cation transporters to move across cell membranes. We previously demonstrated that human and mouse placentas predominantly express organic cation transporter 3 (OCT3), but the impact of this transporter on maternal and fetal disposition of metformin is unknown. Using immunofluorescence colocalization studies in term human placenta, we showed that OCT3 is localized to the basal (fetal-facing) membrane of syncytiotrophoblast cells with no expression on the apical (maternal-facing) membrane. OCT3 positive staining was also observed in fetal capillaries. To determine the in vivo role of OCT3 in maternal and fetal disposition of metformin, we determined metformin maternal pharmacokinetics and overall fetal exposure in wild-type and Oct3-null pregnant mice. After oral dosing of [¹⁴C]metformin at gestational day 19, the systemic drug exposure (AUC_0-∞) in maternal plasma was slightly reduced by ∼16% in the Oct3^-/- pregnant mice. In contrast, overall fetal AUC_0-∞ was reduced by 47% in the Oct3^-/- pregnant mice. Consistent with our previous findings in nonpregnant mice, metformin tissue distribution was respectively reduced by 70% and 52% in the salivary glands and heart in Oct3^-/- pregnant mice. Our in vivo data in mice clearly demonstrated a significant role of Oct3 in facilitating metformin fetal distribution and exposure during pregnancy. Modulation of placental OCT3 expression or activity by gestational age, genetic polymorphism, or pharmacological inhibitors may alter fetal exposure to metformin or other drugs transported by OCT3.

Ethnic differences translate to inadequacy of high-risk screening for gestational diabetes mellitus in an Asian population: a cohort study

BACKGROUND

Universal and high-risk screening for gestational diabetes mellitus (GDM) has been widely studied and debated. Few studies have assessed GDM screening in Asian populations and even fewer have compared Asian ethnic groups in a single multi-ethnic population.

METHODS

1136 pregnant women (56.7% Chinese, 25.5% Malay and 17.8% Indian) from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort study were screened for GDM by 75-g oral glucose tolerance test (OGTT) at 26-28 weeks of gestation. GDM was defined using the World Health Organization (WHO) criteria. High-risk screening is based on the guidelines of the UK National Institute for Health and Clinical Excellence.

RESULTS

Universal screening detected significantly more cases than high-risk screening [crude OR 2.2 (95% CI 1.7-2.8)], particularly for Chinese women [crude OR = 3.5 (95% CI 2.5-5.0)]. Pre-pregnancy BMI > 30 kg/m2 (adjusted OR = 3.4, 95% CI 1.5-7.9) and previous GDM history (adjusted OR = 6.6, 95% CI 1.2-37.3) were associated with increased risk of GDM in Malay women while GDM history was the only significant risk factor for GDM in Chinese women (adjusted OR = 4.7, 95% CI 2.0-11.0).

CONCLUSION

Risk factors used in high-risk screening do not sufficiently predict GDM risk and failed to detect half the GDM cases in Asian women. Asian women, particularly Chinese, should be screened to avoid under-diagnosis of GDM and thereby optimize maternal and fetal outcomes.

Preconception healthcare: what women know and believe

OBJECTIVES

The objectives of this study were to determine if women realize the importance of optimizing their health prior to a pregnancy, whether the pregnancy is planned or not; and to evaluate their knowledge level and beliefs about preconception healthcare. Additionally, we sought to understand how and when women wanted to receive information on preconception health.

METHODS

A survey study was performed using consecutive patients presenting to primary care practices for an annual well-woman exam. Patients were recruited based on appointment type and willingness to complete the survey at the time of their appointment, but prior to being seen by the physician.

RESULTS

A total of 499 women completed the survey. Nearly all women (98.6%) realized the importance of optimizing their health prior to a pregnancy, and realized the best time to receive information about preconception health is before conception. The vast majority of patients surveyed (95.3%) preferred to receive information about preconception health from their primary care physician. Only 39% of women could recall their physician ever discussing this topic. The population studied revealed some significant knowledge deficiencies about factors that may threaten the health of mother or fetus.

CONCLUSIONS

A majority of women do understand the importance of optimizing their health prior to conception, and look to their Primary care physician as their preferred source for such information. Study participants demonstrated deficiencies in their knowledge of risk factors that impact maternal and fetal health suggesting that physicians are not addressing preconception healthcare during routine care.

Oral glucose tolerance testing at gestational weeks < or =16 could predict or exclude subsequent gestational diabetes mellitus during the current pregnancy in high risk group

BACKGROUND

An oral glucose tolerance test with a result that is negative but close to the diagnostic cut-off in early pregnancy was hypothesized to serve as a predictor of subsequent gestational diabetes in a high risk group. The aim of the study was to determine those cut-off values of OGTT at gestational weeks < or =16, which can predict or exclude subsequent onset of GDM in a high risk group.

METHODS

Pregnant women at high risk of gestational diabetes (n = 163) underwent a 2-h, 75-g oral glucose tolerance test at gestational weeks < or =16 were analyzed in this study. In the event of a negative result, subsequent oral glucose tolerance tests were performed at gestational weeks 24-28 and 32-34. The sensitivity, the specificity, the positive and negative predictive values and the Odds ratio of the best cut-off values of fasting and postload glucose levels were calculated.

RESULTS

The best cut-off values to exclude subsequent GDM for fasting and postload glucose were 5.0 and 6.2 mmol/l, respectively. In combination, the best cut-off values were 5.3 mmol/l for fasting and 6.8 mmol/l for postload glucose, with negative predictive values of 0.97 and 0.71 and sensitivities of 96.9 and 86.3 at gestational weeks 24-28 and 32-34, respectively. Combination of these cut-off values with obesity proved to be very predictive for gestational diabetes by gestational weeks 32-34, with an Odds ratio of 6.0 [95% confidence interval: 1.7-21.0].

CONCLUSIONS

With regard to the very high negative predictive value of the method, pregnant women with glucose levels of < or =5.3 mmol/l at fasting and of < or = 6.8 mmol/l at postload in gestational weeks < or =16 should undergo subsequent oral glucose tolerance testing merely at gestational weeks 32-34. Approximately a quarter (24.5%) of the pregnant women at risk of gestational diabetes satisfied these criteria.

Pharmacogenomic assessment of treatment options in gestational diabetes

Gene expression profiles offer a multidimensional view of metabolic diseases, typically characterized by a single parameter, and can provide a basis for choosing between therapies yielding a common clinical end point. We applied such an approach in gestational diabetes mellitus (GDM). Gene expression was examined in four maternal tissues and placentas from normal patients and euglycemic GDM patients, undergoing elective Cesarean sections at term, treated either by diet or diet plus insulin. Deviations from normal were 11-fold greater for the patients treated by diet, alone, than for patients treated by diet plus insulin. Assuming the achievement of a "normal" gene expression profile, in addition to euglycemia, is a desirable outcome of treatment, insulin treatment appears to have a beneficial effect in the treatment of GDM. Subsequently, we utilized the expression data to identify serum biomarkers that provide ways to monitor the benefits of insulin treatment in GDM.