All known type 2 diabetes (T2D) patients in this region are invited to participate (proband). In addition to T2D patients, their family members (parents, siblings, spouses, and children) will also be invited to participate.
Participants fill-out a questionnaire to provide demographic (age, marital status, occupation, education, etc.), lifestyle (exercise, alcohol consumption, smoking etc.), and disease status (diabetes, blood pressure, cardiovascular disease, family history of diabetes, etc.). Trained nurses obtain medication history. Participants undergo physical examinations for assessment their weight, height, fat composition of the body, and ECG. They also undergo laboratory examinations that include blood tests and urine examination. They participate in a 75g oral glucose tolerance test (OGTT) after 10-12 hours of fasting (according to the WHO guidelines). During OGTT, samples of plasma glucose and insulin values will be drawn at 0, 30, 60, and 120 minutes. The blood samples are also tested for lipids, liver function test, antibodies associated with diabetes, and gene analyses. Urine samples are tested for albumin and sugar.
The participants in the study get the personal answers from the research results and, if necessary, a referral to the extended examination and health care. Those without diabetes at baseline (relatives or spouses of patients with type 2 diabetes) will be invited for follow-up examinations every 3-5 years, referred to as Botnia Prospective Study. The follow-up visits follow the same structure as the basal study.
The aim of the Botnia Family Study and Botnia Prospective Study is to examine interaction of lifestyle and genetic factors responsible for developing T2D. Even though Botnia Family Study and Botnia Prospective Study concentrate on the examining of risk factors that mainly affect development of T2D, many other forms of diabetes have been identified in families that participated in these studies. The various other forms described are: MODY–diabetes, LADA-diabetes or and hybrids of the diabetes of type 1 and type 2 (MIX).