Exposure to Phthalates Affects Insulin Resistance in the Elderly

Abstract

O-31C6-5 Background/Aims: High plasma levels of insulin and glucose due to insulin resistance (IR) are believed to be the origin of metabolic syndrome and type 2 diabetes, including its complications. In this study, we tried to determine whether exposure to phthalates affects insulin and glucose levels and HOMA index as IR indices and oxidative stress in elderly. Methods: We recruited 525 of aged persons more than 52 years old and obtained blood and urine samples during 3 medical examinations. We measured urinary level of mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) as DEHP metabolites, and mono-n-butyl phthalate (MnBP) as a DBP metabolite. We also measured levels of insulin and glucose in serum in order to assess IR. In addition, the HOMA, an indirect index for the assessment of IR, was calculated. Malondialdehyde (MDA), an oxidative stress biomarker, was also measured in urine samples. Results: When we estimated the effect of MEHHP, MEOHP, and MnBP on each IR index and MDA level using repeated analysis, all MEHHP, MEOHP, and MnBP levels showed positive relationships with insulin, glucose, HOMA index, and MDA levels after being adjusted for age, sex, BMI, and cotinine level (MEHHP-insulin, β = 0.0954, P = 0.0013; MEOHP-insulin, β = 0.1116, P = 0.0002; MnBP-insulin, β = 0.1149, P = 0.0003; MEHHP-glucose, β = 0.0446, P < 0.0001). Conclusion: Our study results suggest that the exposure to phthalates increases IR and oxidative stress in the elderly.