Proton pump inhibitor (PPI) use has been associated with cardiovascular disease, chronic kidney disease, and dementia. Prior studies did not account for key confounders and little is known about the association of PPIs with serum biomarkers of inflammation, insulin resistance, cardiovascular risk, and renal function. Our aims were to investigate differences in these biomarkers between PPI users and nonusers. Our data are from the National Health and Nutrition Examination Survey (NHANES), a complex cross-sectional multistage probability sample of the US civilian population. We used data on 5189 eligible adults aged 18 to 85 years. Appropriate survey commands were used and potential confounding variables (including BMI, duration of PPI use, use of other non-PPI medications, and health behaviors) were included in multivariable regression models assessing biomarker outcomes. PPI use was associated with differences in mean (±SE) fasting low-density lipoprotein (LDL) (by 11.7±3.7 mg/dL; P=0.006), and apolipoprotein B (by 7.6±2.6 mg/dL; P=0.01). PPI use was not associated with significant differences in total cholesterol (P=0.13), high-density lipoprotein (P=0.27), triglycerides (P=0.70), c-reactive protein (P=0.52), the homeostatic model assessment-insulin resistance (P=0.48), hemoglobin A1c (P=0.39), or homocysteine (P=0.87). PPI use was associated with a decrease in blood urea nitrogen (by 1.0±0.3 mg/dL; P=0.008) but not creatinine (P=0.38) or uric acid (P=0.34). PPI was not associated with clinically significant differences in serum biomarkers of inflammation, insulin resistance, cardiovascular risk, and renal function. Rather, increasing BMI was strongly associated with PPI use and clinically significant differences in these biomarkers.