title: Relatively Low β-Cell Responsiveness Contributes to the Association of BMI with Circulating Glucose Concentrations Measured under Free-Living Conditions among Pregnant African American Women.
abstract: Body mass index (BMI, in kg/m(2)) is positively associated with plasma glucose in late pregnancy and with risk of adverse obstetric outcomes. Much of the existing research uses single-clinic measures of plasma glucose, which may not accurately reflect circulating glucose under free-living conditions. Furthermore, little is known about circulating glucose concentrations of African American women, who tend to have poorer diet quality and a greater risk of obstetric complications.
  
  
  
  The objective of the study was to test the hypothesis that the positive association of BMI in early pregnancy with third-trimester circulating glucose concentrations measured under free-living conditions among African American women would be at least partially attributable to lower β-cell insulin secretion relative to insulin sensitivity [i.e., lower disposition index (DI)].
  
  
  
  Using a prospective, observational design, 40 pregnant African American women (mean ± SD age: 23.1 ± 4.0 y; mean ± SD BMI: 28.4 ± 7.5) wore continuous glucose monitors and accelerometers for 3 d at 32-35 wk of gestation and concurrently maintained a food diary to report their self-selected meals. The DI was derived from a 75-g oral glucose tolerance test. Linear regression modeling was used to calculate the association of BMI with the 24-h glucose (GLUC24h) and 2-h (GLUC2hPP) postprandial glucose areas under the curve and with the percentage of time the glucose concentrations were >120 mg/dL.
  
  
  
  The positive associations between BMI and GLUC24h (standardized β = 0.36, P = 0.03) and the percentage of time glucose concentrations were >120 mg/dL (standardized β = 0.40, P = 0.02) were independent of total carbohydrate intake and physical activity and were attenuated when DI was added to the model. The positive association of BMI with GLUC2hPP was attenuated when DI was added to the model, and DI itself was independently associated with GLUC2hPP after self-selected breakfast and dinner (standardized β = -0.33 and -0.42, respectively; P = 0.01).
  
  
  
  The association of BMI with high circulating glucose in free-living pregnant African American women is at least partially attributable to lower β-cell responsiveness.
authors.affiliation: Departments of Nutrition Sciences, pchandle@uab.edu.
authors.forename: Paula C
authors.initials: PC
authors.lastname: Chandler-Laney
authors.affiliation: Psychology.
authors.forename: Desti N
authors.initials: DN
authors.lastname: Shepard
authors.affiliation: Departments of Nutrition Sciences.
authors.forename: Camille R
authors.initials: CR
authors.lastname: Schneider
authors.affiliation: Sociology.
authors.forename: Lee Anne
authors.initials: LA
authors.lastname: Flagg
authors.affiliation: Clinical and Diagnostic Sciences, and.
authors.forename: Wesley M
authors.initials: WM
authors.lastname: Granger
authors.affiliation: Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Mancuso
authors.affiliation: Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Biggio
authors.affiliation: Departments of Nutrition Sciences.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Gower
mesh_terms: D000328:Adult; D001741:Black or African American; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D016640:Diabetes, Gestational / Q000097:blood; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D015444:Exercise; D005260:Female; D018149:Glucose Intolerance / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000502:physiology*; D009765:Obesity / Q000097:blood / Q000150:complications*; D011247:Pregnancy; D011248:Pregnancy Complications; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin
keywords: carbohydrate; diet; glucose tolerance; insulin sensitivity; β-cell function