The Ely study, established in 1990, is a prospective study of the aetiology of type 2 diabetes and was described in detail elsewhere. The Ely study comprises individuals of European ancestry aged 50–79 years, registered at a single medical practice in Ely, Cambridgeshire, UK and evaluated in three phases. All participants of the Ely study gave their written informed consent and the study was approved by the local ethics committee. Two hundred participants from Ely phase 3 with complete fasting and OGTT sample availability were selected for measurement (105 women / 95 men).