Background: Emerging evidence links early pregnancy (EP) abnormalities in glucose tolerance to adverse outcomes, but glycemic physiology changes in EP are not well characterized. We hypothesized that EP insulin secretory response would be enhanced compared to postpartum (PP), independent of insulin sensitivity.
Methods: To date, 14 women without pre-existing diabetes have undergone 75-gram oral glucose tests with timed measurements of insulin and glucose at 10-15 weeks gestation (EP) and 5-15 weeks after delivery (PP). We tested for a difference in insulin secretory response (Stumvoll 1st phase estimate) in EP compared to PP with adjustment for insulin sensitivity (Matsuda index) using a linear mixed effects model. We explored associations between participant characteristics and the change in insulin secretion between EP and PP using simple linear regression.
Results: Participants had a mean (standard deviation) age of 32.3 (5.0) years and BMI of 27 (4.9) kg/m2; 43% were nulliparous and 43% were racial/ethnic minorities. In EP vs. PP, insulin secretory response (Stumvoll 1st phase estimate) was 1474 (706) vs. 1221 (398) pmol/L, while insulin sensitivity (Matsuda index) was 9.4 (7.2) vs. 9.7 (6.8). Insulin secretory response was significantly enhanced in EP as compared to PP before and after adjustment for insulin sensitivity (β=236, standard error=115, P=0.04 in adjusted model). Lower insulin sensitivity in EP was associated with a greater change in insulin secretory response between EP and PP (β=-42.2, standard error=14.0, P=0.01). There was no association between age, BMI in EP, or the change in BMI between EP and PP and the change in insulin secretory response.
Conclusion: We found evidence of enhancement of insulin secretory response early in pregnancy, in the absence of a change in insulin sensitivity. In light of evidence that identification and treatment of mild glucose intolerance early in pregnancy may be beneficial, larger studies of glycemic physiology in the 1st trimester are warranted.
C.E. Powe: None. J.S. Tangren: None. A. Leong: None. S. Percy: None. S. Krinsky: None. J. Arenas: None. M. Cayford: None. J.C. Florez: Consultant; Self; Intarcia Therapeutics, Inc.. Consultant; Spouse/Partner; Santen. M. Hivert: None. R. Thadhani: None.