Abstract 026: Early Life Exposure to Green Areas and Diabetes Risk, an Assessment From Infancy to Early Teens
Authors: Pescador Jimenez Marcia I , Oken Emily , Gold Diane R , Luttmann-Gibson Heike , Requia Weeberb J , Gingras Veronique , Hivert Marie-France , Rimm Eric B , James Peter 
Published: March 2019

Background:
Increasing empirical evidence suggests that exposure to nature (natural vegetation, or “greenness”) influences health. Studies have shown that greenness is related to lower diabetes risk possibly through mediation of physical activity, harmful environmental exposures, or mental health. However, to our knowledge, no previous study has reported on associations between greenness and insulin resistance in children. We hypothesize that children are more sensitive to environmental exposures particularly during critical windows of susceptibility. Our research aims to evaluate the early life association between greenness and insulin resistance and assess vulnerable life-periods in which individuals are more susceptible to their surroundings.

Methods:
We use data from Project Viva, a longitudinal cohort study designed to study prenatal factors, pregnancy outcomes, and child health. From 1999 to 2002, we recruited pregnant women from a multispecialty group practice in Massachusetts. Of the 1,036 who attended the early teen research visit, we considered 460 participants who provided fasting blood and had complete data for all covariates and exposure at infancy (less than one year), early childhood (median age 3.3 years), mid-childhood (median age 7.7 years) and early teens (median age 13.2). We defined greenness exposure surrounding each participant’s address using 30m resolution Landsat satellite imagery [Normalized Difference Vegetation Index] at infancy (under one year of age), early childhood, mid-childhood, and early teens. Our main outcome measurement was the homeostatic model assessment to estimate insulin resistance (HOMA-IR) at the early teen visit.

Results:
In models adjusted for age, race, sex, mother’s education, father’s education, household income and median household income from the census tract at delivery, living in the highest quintile of greenness in the 90-m area at the early teen visit was associated with 0.65 lower HOMA-IR (95%CI: -1.52, -0.40) than those in the lowest quintile. The observed association between higher greenness exposure and lower HOMA-IR in early teens was consistent for the 270-m area, although slightly attenuated, and no longer significant for the 1230-m area (mean HOMA-IR was 3.06, SD=2.08). We found no associations of exposure to greenness in the 90-m, 270-m or 1230-m areas around participants’ home at infancy, early childhood, or mid-childhood with early teenage HOMA-IR.

Conclusions:
Higher levels of green vegetation, especially closer to the home, at the early teen visit were associated with lower insulin resistance at the same time period. Early exposure to green space during infancy, early childhood and mid-childhood was not associated with HOMA-IR as an early teenager. Early childhood longitudinal studies including geographic contextual factors across diverse populations are needed to confirm or refute these findings.