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17-04-2012 | General practice | Article

Exposure to phthalates linked to diabetes in elderly


Free abstract

MedWire News: High levels of exposure to phthalates increases a person's risk for Type 2 diabetes and insulin resistance, suggest results from the Prospective Investigation of the Vasculature in Uppsala Seniors Study.

Pthalates are used to make plastics flexible and are found in numerous household products such as food packaging, toys, and furniture, as well as medical devices.

"Because it has been reported that phthalate levels in humans are associated with obesity, a well-known effect of peroxisome proliferator-activated receptor (PPAR)-γ receptor activation, and because obesity is an important risk factor for diabetes development, we hypothesized that high levels of phthalates in humans also might be associated with diabetes," explain Monica Lind (Uppsala University, Sweden) and colleagues.

The researchers enrolled 1016 patients, aged 70 years on average, to test for diabetes and insulin resistance.

The participants' sera were tested for exposure to 10 phthalate metabolites using mass spectroscopy, but only four were detected, namely, monomethyl phthalate (MMP), monoisobutyl phthalate (MiBP), monoethyl phthalate (MEP), and mono (2-ethylhexyl) phthalate (MEHP).

Writing in Diabetes Care, the researchers report that following adjustment for gender, body mass index, serum cholesterol and triglycerides, level of education, smoking status, and exercise, high levels of MMP, MiBP, and MEP, but not MEHP, were associated with an increased risk for diabetes.

Analysis of logistic regression models showed that MMP and MiBP were significantly associated with prevalent diabetes (as natural log transformed continuous variables) with adjusted odds ratios (ORs) of 1.21 and 1.30, respectively. A borderline significant association was seen for MEP with an adjusted OR of 1.28 and a nonsignificant association for MEHP with an OR of 0.97.

In addition, the team found that people with MMP, MiBP, and MEP levels in the top versus the bottom quintiles had a 2.0-2.5-fold increased risk for diabetes.

Those with high versus low levels of MEP and MMP also had a significantly increased homeostasis model of insulin resistance index, although this was not seen with the other metabolites.

"Because phthalate metabolites are known ligands to PPARs, receptors known to influence glucose homeostasis, impairments in PPAR-signaling pathways are most likely to contribute to the actions of phthalates on glucose metabolism and diabetes development," suggest Lind et al.

They conclude: "These findings support the view that these commonly used chemicals might influence major factors that are regulating glucose metabolism in humans at the level of exposure of phthalate metabolites seen in the general elderly population."

By Helen Albert

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