Aim: To estimate the progression rates from normal glucose tolerance (NGT), isolated impaired glucose tolerance (IGT), isolated impaired fasting glucose (IFG) and combined IFG/IGT to type 2 diabetes (T2D) in a high risk population with and without hypertension (HTN) in Isfahan, Iran.

Methods: During a mean (SD) follow-up period of 6.8 (1.7) years, 1489 non-diabetic first-degree relatives of patients with T2D with or without HTN were followed for the occurrence of T2D. At baseline and through follow-ups, participants underwent a standard 75g 2-h oral glucose tolerance test. Blood pressure was measured by standardised protocols and HTN was defined according to the criteria of the JNC7.

Results: The progression rate (95% confidence interval) from NGT, isolated IFG, isolated IGT, and combined IFG/IGT to T2D was 10.0 (4.3, 19.6), 21.7 (9.5, 42.3), 28.2 (12.3, 54.7) and 64.7 (41.0, 96.4) per 1000 person-years in participants with HTN and 3.1 (1.5, 4.7), 16.3 (10.3, 24.2), 25.9 (17.0, 37.7) and 57.9 (46.1, 71.7) per 1000 person-years in participants without HTN based on 10,134 person-years of follow-up. Compared with individuals with NGT and without HTN, individuals with NGT and HTN, isolated IFG, isolated IGT, and combined IFG/IGT with or without HTN at baseline were more likely to progress to T2D. Compared with participants without HTN, individuals with concomitant HTN were not significantly more likely to progress to T2D.

Conclusions: Compared with individuals without HTN, the presence of NGT, isolated IFG, isolated IGT, and combined IFG/IGT with concomitant HTN was not associated with higher likelihood of progression to T2D in high-risk individuals in Iran.