The Hoorn Study

The Hoorn Studies were established to investigate the prevalence and risk factors of impaired glucose metabolism, diabetes and diabetes-related complications in a predominately Caucasian population. Its aims were to investigate whether increasing rates of longevity, physical inactivity and obesity affected the prevalence and risk factors of disturbances in glucose metabolism. In 1989 3553 men and women in the age of 50-76 years were invited for the first wave of the study, of which 71% participated. In 2006 the second wave of the Hoorn Studies started with 2748 participants in the age of 40-66 year.

The studies are unique: the first wave of the Hoorn Studies included five follow-up visits over 25 years and the second wave of the Hoorn Studies had two or even three follow-up visits, including extensive (cardio)metabolic profiling. In addition to physical follow-up, data from all participants are linked with registries to retrieve data on occurrence of chronic diseases and causes of death.

In both waves of the Hoorn Studies we determined glucose metabolism, anthropometrics, blood plasma lipid levels, renal function, blood pressure, family history of diabetes as well as several self-reported socio-economic status and behavioural measures. Moreover, in a subgroup of the population, follow up included assessment of diabetes complications retinopathy, nephropathy, autonomic or peripheral nervous system dysfunction as well as cardiac and vascular structure and function. At all visits additional measurements have been conducted, which vary from visit to visit. From each participant, several samples of DNA, plasma, serum, citrate and urine and were stored in our biobank for future use.

The Diabetes Care System

The Hoorn Diabetes Care System cohort (DCS) is a prospective cohort representing a comprehensive dataset on the natural course of type 2 diabetes (T2D), with repeated clinical measures and outcomes. The DCS consists of persons with T2D in primary care from the West-Friesland region of the Netherlands. Enrolment in the cohort started in 1997 and this prospective dynamic cohort currently holds over 15,000 persons with T2D. Approximately 95% of all people with T2D in the region of West-Friesland participate in this cohort.

Clinical measures were collected annually, with a high internal validity due to the centrally organised standardised examinations. Microvascular complications were assessed by measuring kidney function, and screening feet and eyes. Information on cardiovascular disease is obtained by 1) self-report, 2) electrocardiography and 3) electronic patient records. In subgroups of the cohort, biobanking and additional measurements were performed to obtain information on lifestyle, depression and genomics. Finally, the DCS cohort is linked to national registries to retrieve data on care use, the occurrence of chronic diseases and causes of death.

A selection of published findings from the DCS includes identification of subgroups with distinct development of HbA1c, blood pressure and retinopathy, and their predictors; validation of a prediction model for personalized retinopathy screening; the assessment of the role of genetics in development and treatment of T2D, providing options for personalized medicine.

Collaboration and data access: Currently, we are involved in (inter)national projects on, among others, biomarkers and prediction models for T2D and complications and we are interested in collaborations with external researchers.