This study aims at improving the prediction of type 2 diabetes among high-risk individuals by examining glucose excursion patterns in subjects with impaired glucose tolerance. In addition, this study will show whether the currently used diagnostic test could be replaced by an easier and less expensive method.

Type 2 diabetes is a chronic disease of glucose metabolism leading to various disabling conditions. The onset of type 2 diabetes is a gradual shift from normal to abnormal, giving rarely noticeable symptoms at its early stages or even in later stages when damage has already been caused. Due to the gradual onset, the diagnosis is often delayed, and as much as half of the asymptomatic patients remain undetected. The diagnostic criteria for diabetes are based on artificial boundaries reflecting the risk of complications related to diabetes. The golden standard of diagnosis of diabetes is a 2 hours oral glucose tolerance test, which is both time consuming and costly. This study aims at improving the prediction of type 2 diabetes among high-risk individuals by examining glucose excursion patterns in subjects with impaired glucose tolerance. In addition, this study will show whether the currently used diagnostic test could be replaced by an easier and less expensive method.

Inclusion Criteria:

• Individuals with impaired glucose tolerance (2h plasma glucose during oral glucose tolerance test >7.8-11.1 mmol/l, n=50) or with type 2 diabetes (fasting plasma glucose > 7.0 mmol/l and/or 2h plasma glucose > 11.1 mmol/l on two occasions, or both criteria fulfilled in the same oral glucose tolerance test while not pregnant, n=50) with short duration (<3 years); 40 from Padova University Hospital, 60 from the Botnia Study or the PPP (Prevalence, Prediction, Prevention)-Botnia Study in Finland.
• Age 40-75 years

Exclusion Criteria:

• Medication with: insulin, glucagon-like peptide-1 (GLP-1)-analogues, sulphonylureas, oral corticosteroids, thyreostatic agents or thyroid hormone, luteinizing-hormone-releasing hormone (LHRH) analogues
• Pregnancy
• Known changes in retinal fundus photographs
• Known, microalbuminuria
• HbA1c >8%
• Fasting plasma glucose >10 mmol/l
• Medication with metformin, glitazones, gliptins (or acarbose) is allowed but gliptins and acarbose need to be stopped 2 days before testing and during the study

Individuals with impaired glucose tolerance (2h plasma glucose during oral glucose tolerance test >7.8-11.1 mmol/l, n=50) or with type 2 diabetes (fasting plasma glucose > 7.0 mmol/l and/or 2h plasma glucose > 11.1 mmol/l on two occasions, or both criteria fulfilled in the same oral glucose tolerance test while not pregnant, n=50) with short duration (<3 years); 40 from Padova University Hospital, 60 from the Botnia Study or the PPP-Botnia Study in Finland. The Botnia Study and the PPP-Botnia Study are population based studies investigating type 2 diabetes in western Finland.