Reasons for non-response in the HbA1c group and the OGTT group.

OGTT group = people offered screening by means of an oral glucose tolerance test; HbA1c group = people offered screening by means of a glycated hemoglobin measurement; Not eligible = outside age range, longterm illness, currently pregnant, already participating in other research project(s), moved away from The Hague; Unknown = no contact established or no reason provided during telephone contact or on reply card; OGTT = oral glucose tolerance test.