Associations of neonicotinoids with insulin and glucose homeostasis parameters in US adults: NHANES 2015-2016

Neonicotinoids are replacement insecticides increasingly used for organophosphates, methylcarbamates, and pyrethroids. Experimental evidence suggests neonicotinoids may affect glucose metabolism and insulin secretion through pancreatic beta cell dysfunction, oxidative stress, and inflammation. However, no epidemiologic study has investigated neonicotinoids as potential diabetogens. We examined associations between neonicotinoids with insulin and glucose homeostasis parameters among 1381 non-diabetic adults in the National Health and Nutrition Examination Survey (2015-2016). Urinary concentrations of acetamiprid, clothianidin, imidacloprid, N-desmethyl-acetamiprid, and 5-hydroxy-imidacloprid were quantified. Fasting plasma glucose, insulin, and hemoglobin A(1c) (HbA(1c)) were assessed. Insulin resistance was defined as a homeostatic model assessment of insulin resistance >= 2.5. We used weighted linear and logistic regression to estimate associations between detectable neonicotinoids with insulin and glucose homeostasis parameters compared to non-detectable neonicotinoid concentrations. Weighted detection frequencies for imidacloprid, 5-hydroxy-imidacloprid, and N-desmethyl-acetamiprid were 4.4 %, 21.5 %, and 32.8 %, respectively. Detectable imidacloprid (beta = 4.7 mu IU/mL, 95 % confidence interval [CI] -8.5, 0.8) and 5-hydroxy-imidacloprid (beta = 2.4 mu IU/mL, 95 % CI -4.6, 0.2) were associated with lower fasting plasma insulin levels. Individuals with detectable 5-hydroxy-imidacloprid had lower odds of insulin resistance (odds ratio [OR] = 0.3, 95 % CI 0.2, 0.7). We observed evidence of sexually dimorphic associations between N-desmethyl-acetamiprid with glucose (pint = 0.079) and 5-hydroxy-imidacloprid with HbA(1c) (p(int) = 0.038), with patterns suggesting positive associations in males and negative associations in females. Associations between 5-hydroxy-imidacloprid and insulin were modified by body mass index (BMI) (p(int) = 0.013). We additionally observed age modified associations between 5-hydyroxy-imidacloprid and glucose (p(int) = 0.048). Results suggest neonicotinoids may be associated with insulin and glucose homeostasis indices and call for prospective studies to examine the metabolic impact of these replacement insecticides in humans.

Automated summary

Neonicotinoids, a new class of insecticides, may have an impact on insulin and glucose homeostasis parameters, with certain chemicals such as imidacloprid and 5-hydroxy-imidacloprid showing negative associations with insulin levels. Sex, body mass index, and age may also modulate these associations.