The evolution of 2 h post-load glucose tolerance test for diagnosis of diabetes and its clinical implication was reviewed and discussed.Post-load hyperglycemia is a risk factor for both micro-and macro-vascular diseases.According to its relationship with retinopathy,the current cut-off values for diabetes was defined since 1979.Recently,strong evidence has shown that post-load hyperglycemia is also an important risk factor for cardiovascular disease(CVD),the relation is linear and no a threshold was found.There are large discrepancies between fasting and 2 h glucose criteria in the classification of diabetes and impaired glucose tolerance(IGT)/impaired fasting glucose(IFG).For early diagnosis and intervention administrating a 2 h OGTT to suspect individuals is necessary.