The New and Safer Gold Standard in Predicting Gestational Diabetes during the COVID-19 Pandemic

Introduction: Approximately 6–9% of births occurring in the US each year are complicated by gestational diabetes (GDM). GDM is a major risk factor for complications from COVID-19 infection and healthcare providers should aim to keep exposure risk low for pregnant women by avoiding repetitive, or lengthy visits outside of their homes.

Objective: This study sets out to determine if measuring fasting insulin (FI) levels during pregnancy can predict abnormal OGTT results, helping identify mothers with GDM earlier and more accurately. This new method could potentially save time and money while reducing COVID-19 exposure risk.

Methods: The study was conducted in Bakersfield CA from November 2016 to June 2017 and included two cohorts of pregnant women at 24+ weeks’ gestation. FI levels were drawn on the women while receiving either a 1-step glucose tolerance test (fasting and 2-hour blood glucose level after a 75 g glucose drink) or a 2-step (3-hour tolerance test after failing the 1-hour 50 g glucose test). Their glucose levels were interpreted using recommendations from the ADA (2HOGTT) and Carpenter and Coustan (3HOGTT). Insulin levels due to insulin resistance were also predicted using the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), using the formula (FI)(FG)/405. FI levels and HOMA-IR values were compared with the 3HOGTT results using 2 criteria to measure the viability of the results. Criteria #1 was defined as an abnormal value for any one indicator and Criteria #2 was defined as two abnormal values.

Results: There were 104 patients in the 2HOGTT cohort and 115 patients in the 3HOGTT cohort. Predictive graphs were used to calculate the threshold values for FI and HOMA-IR to predict GDM based on the 2HR test and Criteria #1 and #2 as detailed above for 3HR. Those values were used to create indicator variables. All predictors were found to be statistically significant in a logistic regression model (all p-values ≤ 0.0001), demonstrating that the FI levels and HOMA-IR met criteria for detecting risk of GDM just as accurately as 1 and 2-step processes.

Conclusion: The significant association between positive 2HOGTT test results and a 2H FI and HOMA-IR, and the 3HOGTT meeting both Criteria #1 and #2 indicates that this simple and cost-effective laboratory test in routine prenatal care is a promising intervention to accurately detect GDM. Utilizing FI insulin levels may even be able to lead to a GDM diagnosis sooner than a one or two-step screening test, leading to better maternal and infant outcomes.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
17 September 2021