Background Fasting plasma glucose (FPG) and 2-h post challenge plasma glucose (2 h-PCPG), whether as continuous or categorical variables, are associated with incident cardiovascular disease (CVD) and diabetes; however, their role among patients with existing CVD is a matter of debate. We aimed to evaluate associations of different glucose intolerance states with recurrent CVD and incident diabetes among subjects with previous CVD. Methods From a prospective population-based cohort, 408 Iranians aged  ≥  30 years, with history of CVD and without known diabetes were included. Associations of impaired fasting glucose (IFG) according to the American Diabetes Association (ADA) and World Health Organization (WHO) criteria, impaired glucose tolerance (IGT), newly diagnosed diabetes (NDM) with outcomes of interest were determined by multivariable Cox proportional hazard models after adjustment for traditional risk factors. Furthermore, FPG and 2 h-PCPG were entered as continuous variables. Results Over a decade of follow-up, 220 CVD events including 89 hard events (death, myocardial infarction and stroke) occurred. Regarding prediabetes, only IFG-ADA was associated with increased risk of hard CVD [hazard ratio(HR), 95%CI: 1.62,1.03–2.57] in the age-sex adjusted model. In patients with NDM, those with FPG ≥ 7 mmol/L were at higher risk of incident CVD/coronary heart disease(CHD) and their related hard outcomes (HR ranged from 1.89 to 2.84, all P < 0.05). Moreover, those with 2 h-PCPG ≥ 11.1 mmol/L had significant higher risk of CVD (1.46,1.02–2.11), CHD (1.46,1.00–2.15) and hard CHD (1.95:0.99–3.85, P = 0.05). In the fully adjusted model, each 1 SD increase in FPG was associated with 20, 27, 15 and 25% higher risk of CVD, hard CVD, CHD and hard CHD, respectively; moreover each 1 SD higher 2 h-PCPG was associated with 21% and 16% higher risk of CVD, and CHD, respectively. Among individuals free of diabetes at baseline (n = 361), IFG-ADA, IFG-WHO and IGT were significantly associated with incident diabetes (all P < 0.05); significant associations were also found for FPG and 2 h-PCPG as continuous variables (all HRs for 1-SD increase > 2, P < 0.05). Conclusions Among subjects with stable CVD, NDM whether as high FPG or 2 h-PCPG, but not pre-diabetes status was significantly associated with CVD/CHD and related hard outcomes.

Background: To assess the association between fasting plasma glucose (FPG) and 2-h post challenge plasma glucose (2h-PCPG) as continuous or categorical variables with risk of recurrent cardiovascular disease (CVD) and incident diabetes among subjects with history of previous CVD. Methods: In a prospective population-based cohort, a total of 335 Iranians aged ≥30 years, with history of CVD and free of known diabetes were included. Prediabetes was defined as impaired fasting glucose (IFG) according to the criteria of the American Diabetes Association (ADA) [IFG-ADA; FPG: 5.6-6.9 mmol/L], the World Health Organization (WHO) expert group (IFG-WHO; FPG: 6.1-6.9 mmol/L) and impaired glucose tolerance [IGT: 2h-PCPG: 7.8-11.0 mmol/L]. Cox’s proportional hazard models adjusted for traditional risk factors were used to estimate the hazard ratio (HR) with 95% confidence interval (CI) of different glucose intolerance for outcomes of interest. Results: During a median follow-up of 15.8 (IQR, 10.7-16.5) years, 178 CVD (hard event including death, myocardial infarction and stroke=69) events occurred. Regarding FPG, only IFG-ADA was associated with significant higher risk of hard CVD in the fully adjusted model (HR, 1.73, 95% CI: 1.04-2.89). Moreover, newly diagnosed diabetes (FPG≥7 mmol/L) was an independent risk of CVD (2.11: 1.22-3.66). Focusing on 2h-PCPG, subjects with newly diagnosed diabetes (2h-PCPG ≥ 11.1 mmol/L) had moderately increased risk of hard coronary heart disease (2.02:0.91-4.47, P=0.08). The multivariate HRs (95% CI) associated with 1 SD increase in FPG and 2h-PCPG was 1.16 (1.01–1.33) and 1.19 (1.02–1.38) for CVD, respectively. Among population free of diabetes at baseline (n=270), IFG-ADA, IFG-WHO and IGT were significantly associated with incident diabetes in multivariate analysis (all HRs > 4, P< 0.001); significant associations were also found for FPG and 2h-PCPG as continuous variables (all HRs for 1-SD increase > 2, all P < 0.001). Conclusions: Among subjects with stable CVD, both FPG and 2h-PCPG as continuous variables was associated with higher risk of recurrent CVD. However, only IFG-ADA was independent predictor of hard CVD events. Also, newly diagnosed diabetes, using FPG criteria, was associated with a significant risk of CVD. IFG-ADA, IFG-WHO and IGT were all significant predictors of incident diabetes.