Association between neck circumference and glucose tolerance levels at 2-6 months postpartum in women with and without gestational diabetes

ABSTRACT Objective: To evaluate the association between neck circumference (NC) measured during pregnancy and markers of glucose metabolism measured 2-6 months postpartum in women with overweight/obesity with and without gestational diabetes (GDM). Subjects and methods: This prospective study enrolled 100 pregnant women (including 50 with GDM) with pregestational body mass index (BMI) ≥ 25 kg and < 40 kg/m². The cohort was stratified according to NC tertiles during pregnancy. Glucose metabolism was assessed in the postpartum period. The association between NC during pregnancy and markers of glucose metabolism postpartum was tested using linear regression analysis. Results: Participants with NC in the third tertile, compared with those with NC in the second and first tertiles, had higher levels of glycated hemoglobin (HbA1c; 5.6 ± 0.4% versus 5.4 ± 0.3% versus 5.3 ± 0.2%, respectively, p = 0.006), fasting insulin (13.2 ± 6.6 µIU/mL versus 11.1 ± 5.8 µIU/mL versus 9.5 ± 4.9 µIU/mL, respectively, p = 0.035), homeostasis model for insulin resistance (HOMA-IR; 3.1 ± 1.7 versus 2.5 ± 1.3 versus 2.1 ± 1.2, respectively, p = 0.035) and triglyceride-glucose index (TyG; 4.6 ± 0.2 versus 4.5 ± 0.2 versus 4.5 ± 0.3, respectively, p = 0.010). In crude linear regression analysis, NC measured during pregnancy was significantly associated with levels of fasting plasma glucose, 2-hour glucose, HbA1c, log HOMA-IR, and TyG index. The association remained after adjustment for age, family history of diabetes, and number of pregnancies. When adjusted for pregestational BMI and gestational weight gain, NC remained independently associated with fasting plasma glucose and HbA1c levels. Conclusion: The NC measured during pregnancy was positively associated with worse glucose metabolic profile in the postpartum among women with obesity/overweight with and without GDM. The NC measurement may be a feasible tool for early identification of women at a higher risk of developing type 2 diabetes mellitus.

Prolactin does not seem to mediate the improvement on insulin resistance markers and blood glucose levels related to breastfeeding.

Introduction: The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. Strategies to decrease this risk should be strongly encouraged. Lactation has been associated, for the mother, with reduction in future T2DM risk in several studies. The mechanisms behind this phenomenon, however, are poorly understood. The aims of this study were, first, to compare blood glucose levels and markers of insulin resistance (MIR) in early postpartum women with overweight/obesity according to their breastfeeding status and, second, to evaluate whether prolactin (PRL) levels could mediate improvements in these parameters. Methods: The prospective study followed 95 women older than 18 years from early pregnancy for up to 60 to 180 days postpartum. All participants had a BMI > 25 kg/m2 and a singleton pregnancy. At each visit, questionnaires and clinical and biochemical evaluations were performed. Participants were divided into two groups according to the breastfeeding status as "yes" for exclusive or predominant breastfeeding, and "no" for not breastfeeding. Results: Breastfeeding women (n = 44) had significantly higher PRL levels [47.8 (29.6-88.2) vs. 20.0 (12.0-33.8), p< 0.001]. They also had significantly lower fasting blood glucose levels [89.0 (8.0) vs. 93.9 (12.6) mg/dl, p = 0.04], triglycerides (TG) [92.2 (37.9) vs. 122.4 (64.4) mg/dl, p = 0.01], TG/HDL ratio [1.8 (0.8) vs. 2.4 (1.6) mg/dl, p = 0.02], TyG index [8.24 (0.4) vs. 8.52 (0.53), p = 0.005], fasting serum insulin [8.9 (6.3-11.6) vs. 11.4 (7.7-17.0), p = 0.048], and HOMA-IR [2.0 (1.3-2.7) vs. 2.6 (1.6-3.9), p = 0.025] in the postpartum period compared to the non-breastfeeding group. Groups were homogeneous in relation to prevalence of GDM, pre-gestational BMI, as well as daily caloric intake, physical activity, and weight loss at postpartum. Linear regression analysis with adjustments for confounders showed a statistically significant association of breastfeeding with fasting blood glucose [-6.37 (-10.91 to -1.83), p = 0.006], HOMA-IR [-0.27 (-0.51 to -0.04), p = 0.024], TyG index [-0.04 (-0.06 to -0.02), p = 0.001], and TG/HDL ratio [-0.25 (-0.48 to -0.01), p = 0.038]. Mediation analysis showed that PRL did not mediate these effects. Sensitivity analyses considering different cutoffs for PRL levels also did not show modification effect in the mediation analyses. Conclusion: Breastfeeding was associated with improvement in glucose metabolism and MIR 60 to 180 days after birth in overweight and obese women, even when adjusted for confounders. PRL levels were not found to mediate the association between breastfeeding and improvement in MIR.

Neck circumference as a predictor of gestational diabetes and risk of adverse outcomes in pregnancy of Brazilian woman with overweight and obesity

ABSTRACT Objective: To evaluate the association of neck circumference (NC) with gestational diabetes (GDM) and adverse outcomes in women with overweight and obesity. Subjects and methods: This prospective study included 132 (BMI > 25 kg/m2) pregnant women without and with GDM. Standardized questionnaire and biochemical/physical evaluation were performed during the 1st to 3rd trimester. Fifth-five women were evaluated regarding hypertension in pregnancy, type of delivery and neonatal complications (death, intensive care unit admission and hypoglycemia). Results: Women with (n = 61) and without (n = 71) GDM had similar mean (SD) pre-gestational BMI [30.3 (4.0) vs. 29.4 (3.5) kg/m2, p = 0.16]. Women with GDM were older [32 (6) vs. 28 (6) yrs, p < 0.001] and had greater NC [36.0 (2.7) vs. 34.5 (1.8) cm, p < 0.001]. NC was similar in women with GDM diagnosed in first or third trimester [p = 0.4] and was correlated with FPG [r 0.29, p = 0.01] and systolic [r 0.28, p = 0.001] and diastolic [r 0.25, p = 0.004] blood pressure. NC was associated with GDM [OR 1.25, 95%CI 1.03-1.52] adjusted for age, physical activity, education and familiar history of diabetes. In ROC analysis, the area under the curve was 0.655 and the cut-off value of 34.5 cm had 0.70 of sensitivity and 0.51 of specificity for GDM. Women who had NC ≥ 34.5 vs. < 34.5 cm had higher frequencies of hypertension [32.3 vs. 4.2%, p = 0.01]. Conclusions: In a group of pregnant women with overweight or obesity, NC can be a useful tool for identifying risk of GDM and obstetric adverse outcomes.