Bisphenol A (BPA) is a widely used synthetic chemical present in many consumer products and has been linked to increased risk of type 2 diabetes in observational studies. Prior to this trial, no experimental human studies had directly tested whether BPA reduces peripheral insulin sensitivity. The trial aimed to determine the effect of short-term oral BPA administration on peripheral insulin sensitivity measured by the gold-standard clamp technique.
This was a randomized, double-blind, placebo-controlled parallel trial published in the Journal of Clinical Endocrinology & Metabolism (2026; DOI: 10.1210/clinem/dgag124; PMID: 41866316). Forty sedentary but otherwise healthy adults were enrolled (22 female, 18 male). Mean reported age was 21.3 ± 2.1 years and mean BMI was 22.1 ± 2.3 kg/m2. The sample was 85% non-Hispanic White according to the abstract. Study enrollment and progress through trial phases are summarized in a CONSORT diagram in the full report.
All participants completed a two-day baseline period consuming an energy-balanced diet low in BPA. During this baseline interval, urine and blood samples were collected and peripheral insulin sensitivity was quantified using a 120-minute euglycemic hyperinsulinemic clamp (insulin infusion 40 mU/m2/min targeting blood glucose of 90 mg/dL). These baseline measures served for within-subject comparison to post-treatment values.
In a double-blind procedure, participants were randomized to one of two arms for five days: oral BPA at 50 µg/kg body weight (BPA-50) or matched placebo (PL). Throughout the intervention all participants remained on the same energy-balanced diet. Treatment allocation and blinding details are provided in the full text.
The primary outcome was change in peripheral insulin sensitivity as measured by the 120-minute euglycemic hyperinsulinemic clamp. The reported metric for insulin sensitivity is mg/kg/min per μU/mL (insulin-normalized glucose disposal).
Secondary measures reported in the abstract included urinary BPA concentrations (to confirm exposure), body weight, fasting glucose, and clamp-derived time courses for insulin, C-peptide, free fatty acids (FFA), and glucose. Figures in the publication present urinary BPA changes, clamp insulin-sensitivity comparisons between groups, and metabolic profiles during clamps.
Outcomes were analyzed using two-way repeated-measures analysis of variance with adjustments for baseline sex, BMI, physical activity, and ethnicity. Group-by-time comparisons for primary and secondary outcomes are reported; specific model outputs beyond the reported P values are available in the full manuscript.
Urinary BPA concentrations increased substantially in the BPA-50 group compared with placebo after treatment (+268,700 ± 63,983 vs +8,893 ± 6,786 pg/mL), confirming effective augmentation of BPA exposure in the active arm (P = .009).
Body weight and fasting glucose did not differ significantly between BPA-50 and placebo after treatment (P > .05), indicating no detectable short-term effect on these measures during the 5-day exposure.
Crucially, peripheral insulin sensitivity decreased in the BPA-50 group by 0.02 ± 0.01 mg/kg/min/uU/mL, whereas the placebo group experienced an increase of 0.02 ± 0.01 mg/kg/min/uU/mL over the same period. The between-group difference was statistically significant (P = .01). These clamp-derived data provide experimental human evidence that short-term oral BPA administration can reduce insulin sensitivity.
The publication includes: a CONSORT diagram and protocol overview (Figure 1); change in urinary BPA concentrations for BPA-50 versus placebo (Figure 2); comparison of insulin sensitivity at baseline and post-treatment and change scores (Figure 3); and clamp time courses for insulin, C-peptide, FFA, and glucose in both groups (Figure 4). These figures illustrate the exposure manipulation and the direction and magnitude of insulin-sensitivity changes reported in the abstract.
In this controlled, randomized human trial, 5 days of oral BPA administration at 50 µg/kg decreased peripheral insulin sensitivity measured by euglycemic hyperinsulinemic clamp in healthy normal-weight adults. The findings represent the first experimental human evidence that BPA exposure may reduce insulin sensitivity, offering a potential mechanistic link to observational associations between BPA exposure and type 2 diabetes risk. Details on longer-term effects, dose–response, and generalizability beyond the studied population are not reported in the abstract and require consultation of the full text for further subgroup and methodological information.
For reference, the trial is reported in J Clin Endocrinol Metab (2026 Aug 13;111(9):2610-2619) with DOI 10.1210/clinem/dgag124 and PMID 41866316.