Incidence of T2DM and the role of baseline glycaemic status as a determinant in a metropolitan population in northern Madrid (Spain)

Aim: To estimate the incidence of T2DM and assess the effect of pre-T2DM (isolated impaired fasting glucose [iIFG], isolated impaired glucose tolerance [iIGT] or both) on progress to T2DM in the adult population of Madrid. Methods: Population-based cohort comprising 1,219 participants (560 normoglycaemic and 659 preT2DM [418 iIFG, 70 iIGT or 171 IFG-IGT]). T2DM was defined based on fasting plasma glucose or HbA1c or use of glucoselowering medication. We used a Cox model with normoglycaemia as reference category. Results: During 7.26 years of follow-up, the unadjusted incidence of T2DM was 11.21 per 1000 person-years (95 %CI, 9.09-13.68) for the whole population, 5.60 (3.55-8.41) for normoglycaemic participants and 16.28 (12.78-20.43) for pre-T2DM participants. After controlling for potential confounding factors, the baseline glycaemic status was associated with higher primary effect on developing T2DM was iIGT (HR = 3.96 [95 %CI, 1.93-8.10]) and IFG-IGT (3.42 [1.92-6.08]). The HR for iIFG was 1.67 (0.96-2.90). Obesity, as secondary effect, was strongly significantly associated (HR = 2.50 [1.30-4.86]). Conclusions: Our incidence of T2DM is consistent with that reported elsewhere in Spain. While baseline iIGT and IFG-IGT behaved a primary effect for progression to T2DM, iIFG showed a trend in this direction.