New diagnostic criteria have recently been proposed that will result in a higher proportion of individuals being diagnosed as suffering from gestational diabetes mellitus (GDM) than previously. The present circum-Mediterranean study sets out to identify the relevance of the new criteria in this population. The study was a prospective, non-interventional, multicentre study in the Mediterranean region. A convenient sample of 1,368 pregnant women was recruited. All participants underwent a 75 g oGTT subdivided into five different glycaemic categories. The women's anthropomorphic and biological data, together with obstetric and infant outcomes, were collected. There was a threefold increase in diagnosis using the new criteria. Most of the biological characteristics generally associated with GDM showed high specificity and low sensitivity values. The biological characteristics, including maternal age, BMI and FBG, showed a progressive increase as a function of maternal glycaemia with moderate sensitivity and specificity values. Using these latter characteristics in combination ensures that 72.3 % of the GDM population would be correctly identified, while an oGTT would only be required in 18.7 % of the population. The progressive relationship of increasing glycaemia to adverse characteristics suggests that the new IADPSG criteria are reasonable provided that dietary advice is given to all pregnant women. In situations of economic restraints, it appears possible to screen Mediterranean women for GDM risk using a composite model using FBG >5.0 mmol/l combined with the performance of an oGTT in women with a low FBG but who are overweight and aged >30 years.