Study links phthalates to type 2 diabetes in elderly

Phthalate metabolites, chemicals commonly used in plastics, cosmetics, and pharmaceuticals, were linked to an increased risk for the development of type 2 diabetes in the elderly, a recent study found.

The study, led by P. Monica Lind, PhD, from the Department of Occupational and Environmental Medicine, Uppsala University, Uppsala, Sweden, was published online April 12 in Diabetes Care.

Phthalates are industrial chemicals used to make plastic products more flexible, the authors explain. The chemicals are additives and not bound to the plastic, so they can easily leach and transfer to air and food. Exposure has been associated with several health conditions, including obesity, asthma, and allergies, the authors note.

Phthalates can bind to certain nuclear peroxisome proliferator-activator receptors (PPARs), which are involved in adipose tissue and lipid homeostasis, and PPAR antagonists are used to treat type 2 diabetes, they explain.

“Because it has been reported that phthalate levels in humans are associated with obesity, a well-known effect of PPAR-g 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,” the authors stated.

Lind and colleagues analyzed data from the Prospective Vasculature in Uppsala Seniors Study. The researchers measured serum levels for 10 phthalate metabolites in 1,016 patients aged 70 years after an overnight fast.

Four metabolites were detected in 96% of the patients by an API 4000 liquid chromatograph/tandem mass spectrometer: mono(2-ethylhexyl) phthalate (MEHP), monomethyl phthalate (MMP), monoethyl phthalate (MEP), and monoisobutyl phthalate (MiBP). The authors note that MEHP is used as a plasticizer but the common feature of the remaining 3 metabolites is that they are derived from the degradation of associated compounds used in personal care products.

Type 2 diabetes, defined as the use of pharmacological hypoglycemic agents or a fasting plasma glucose >7.0 mmol/L, was detected in 114 patients.

After adjusting for sex, high levels of MMP, MEP, and MiBP were associated with an increased prevalence of diabetes among the population. MiBP levels were inversely related to poor insulin secretion, while MEP and MMP levels were related to insulin resistance.

Although the authors admit that the study findings cannot be extrapolated to other ethnicities and age groups due to the population’s homogenous nature, they conclude that the evidence suggests a relationship between the presence of several phthalate metabolites and diabetes prevalence and markers of insulin secretion and resistance.