Aims: First degree relatives (FDRs) of people with type 2 diabetes are at greater cardiovascular and diabetes risk. It is not known whether they are also at greater risk of metabolic syndrome (MetS). The objectives of present study were to assess the incidence of and risk factors for the development of MetS in FDRs of patients with type 2 diabetes.

Methods: A total of 3217 (842 men and 2375 women) FDRs of consecutive patients with type 2 diabetes aged 30-70 years in 2003-2005 were followed through 2010. At baseline participants underwent a standard 75g 2-h standard OGTT and HbA1c measurements. MetS was defined by the NCEP-ATP III. The study group consisted of 734 participants without MetS and history of known diabetes at baseline and had at least one subsequent review in mean (SD) follow-up period of 5.5 (1.2) years.

Results: The prevalence of MetS was 35.8% (95% CI: 34.2, 37.5). The incidence of MetS was 4.3% (95% CI: 3.7, 4.9) (4.6% men and 4.2% women) per year. Multivariate analysis revealed that impaired glucose tolerance (IGT) (RR 1.89 (95% CI: 1.28, 2.79)), impaired fasting glucose (IFG) (RR 1.39 (95% CI: 1.10, 1.73)) and lower HDL (RR 1.34 (95% CI: 1.12, 1.60)) were associated with MetS.

Conclusions: The findings of this study illustrate for the first time the incidence of MetS in FDRs of patients with type 2 diabetes in Iran. Risk of MetS may increases with IGT, IFG and lower HDL.

Keywords: First degree relatives; Metabolic syndrome; Risk factors Incidence