Inflammation and Stress Biomarkers Mediate the Association between Household Food Insecurity and Insulin Resistance among Latinos with Type 2 Diabetes

Background: Household food insecurity (HFI) is a stressor that is associated with type 2 diabetes (T2D). However, little is known about HFI and the insulin resistance (IR) underlying T2D, and the mechanisms involved. Objective: We examined the cross-sectional association between HFI and IR among low-income Latinos with T2D and tested whether inflammation and stress hormones mediated this association. Methods: HFI was measured with the 6-item US Household Food Security Survey module. IR was calculated from fasting plasma blood glucose and serum insulin. Inflammation was indicated by high-sensitivity C-reactive protein (hsCRP), and stress hormones included urinary cortisol, metanephrine, and normetanephrine. To test for an indirect effect of HFI on homeostasis model assessment of IR, a parallel multiple mediation model was run with biological markers that significantly differed between food security status-entered as mediators in the model. We used 95% bias-corrected bootstrap CIs, with 10,000 bootstrap samples, to assess the significance of the indirect effects. Results: The 121 participants with T2D were primarily Puerto Rican (85.8%), aged mean = 60.7 y, and 74% were female. Eighty-two (68%) were classified as food insecure. Compared with food-secure individuals, food-insecure individuals had a significantly higher IR [mean difference (Delta) = 7.21, P = 0.001], insulin (Delta = 9.7, P = 0.019), glucose (Delta = 41, P < 0.001), hsCRP (Delta = 0.8, P = 0.008), cortisol (Delta = 21, P = 0.045), and total cholesterol (Delta = 29, P = 0.004). Groups did not differ on other lipids, metanephrine, normetanephrine, or A1c. The mediation model showed a significant direct effect of HFI on hsCRP (P = 0.020) and on cortisol (P = 0.011). There was a direct effect of cortisol (P = 0.013), hsCRP (P = 0.044), and HFI on IR (P = 0.015). The total combined indirect effect of HFI through cortisol and hsCRP indicated partial mediation. Conclusions: Among Latinos with T2D, HFI is associated with IR partially through inflammation and stress hormones. Interventions to ameliorate HFI and mitigate its effects on inflammation, stress, and IR are warranted. This trial was registered at clinicaltrials.gov as NCT01578096.