Exploring the Association Between Phthalates Exposure, Measured Through Their Urinary Metabolites, and Renal Function Impairment in Individuals With TYpe 2 Diabetes - Protocol 2

The global incidence of diabetic nephropathy (DN) is increasing, with no appreciable reduction in the percent of patients progressing toward end stage renal disease (ESRD) and dialysis (Tuttle et al, 2014, Winocour et al, 2018). Therefore, identification of modifiable risk factors and early biomarkers of progressive decline in kidney function is an urgent clinical need. Phthalates are environmental and dietary contaminants with a various array of use that are identified in many consumer and industrial products; among them, di-(2-ethylhexyl) phthalate (DEHP) and its metabolites (mono 2-ethylhexyl phthalate (MEHP), 5OH-MEHP (MEHHP) and 5oxo-MEHP (MEOHP)) are widely used (Kato et al 2004, Braun et al, 2013). They partially distribute to the human tissues and their urinary and serum levels are directly related; therefore, urinary concentration of phthalates is commonly used as proxy of their exposure in humans (Kato et al 2004).

While the association between phthalates exposure and development of T2D is currently being explored (Dong et al 2017, Dales et al, 2018), little is known about their role in DN. Recent observations show that DEHP and its metabolites are associated with a higher prevalence of low-grade albuminuria and in children exposed to higher phthalates concentrations (Trasande et al, 2014, Wu et al, 2018), however such association has yet to be verified in adults. The environmental ubiquity of the phthalates enhances the importance of investigating the potential relation between their exposure and different degrees of renal function. (Kato et al 2004, Kataria et al, 2015).

Given this premise, the investigators will explore this potential association in a population of subjects with T2D consecutively referring to the outpatient diabetes clinic in Santa Chiara Hospital, Pisa, enrolled on a volunteer basis. During their routine visit at Santa Chiara Hospital outpatient diabetes clinic participants will provide the results of blood tests prescribed as per standard clinical practice along with a first morning, overnight fasting, urine sample collected in a phthalates-free container.

The investigators will record the participants' clinical history, physical examination and anthropometric measurements, will measure their renal function, evaluated by eGFR (calculated with the CDK-EPI formula), albumin excretion, fasting glucose, HbA1c%, and the exposure to phthalates, assessed by total concentrations of MEHP, MEOHP, MEHHP and adjusted for urinary creatinine. In this way, the investigators aim to point out the relationship of urinary phthalates with higher degrees of albuminuria and/or lower eGFR after adjustment for all potential confounders, including therapies.