BACKGROUND: Hypertension is an insulin resistant condition and frequently associated with abnormal glucometabolic state. Early detection and monitoring of dysglycemia (diabetes and pre-diabetes) in hypertensive patients are important to reduce target organ damage and to select antihypertensive medication. 2007 ESH/ESC guideline for the management of hypertension recommends a glucose tolerance test when fasting plasma glucose (FPG) >100 mg/dL in hypertensive patients. However, FPG does not always represent abnormal glucometabolic state in hypertensive patients as well as in a general population. METHODS: From outpatient clinics, we prospectively enrolled 979 primary hypertensive patients (mean age, 56.0짹10.8 years; women, 465; untreated, 275) without known diabetes, coronary artery disease, stroke, heart failure, renal failure, and peripheral arterial disease. Fasting plasma lipids, FPG, and 2h plasma glucose (PG) after ingestion of a 75g glucose load were measured. Relations between metabolic syndrome components and postload dysglycemia were analysed. RESULTS: Prevalence of incident diabetes by FPG criteria was 6.5%. In 365 patients with a normal FPG level, postload hyperglycemia (2h PG ���140 mg/dL) was associated with abdominal obesity (29.8 vs 13.1%, p<0.001) and hypertriglyceridemia (31.5 vs 19.5%, p=0.011). The prevalence of postload hyperglycemia was markedly increased when both abdominal obesity and hypertriglyceridemia were present ���37.5 vs 11.9% (reference: neither abdominal obesity nor hypertriglyceridemia), OR 4.45, 95% CI 2.12-9.34, p<0.001���. In 550 patients with a FPG level 100-125 mg/dL, diabetes by 2h PG criteria was associated with abdominal obesity (13.7 vs 7.6%, p=0.047) and a FPG level ���110 mg/dL (20.3 vs 6.6%, p<0.001). In these patients with impaired fasting glucose, the prevalence of diabetes was increased when abdominal obesity and a FPG level ���110 mg/dL were present ���24.2 vs 6.2% (reference: no abdominal obesity and a FPG level of 100-109 mg/dL), OR 4.84, 95% CI 1.96-11.94, p=0.001���. CONCLUSION: Further work-up for dysglycemia should be considered when hypertriglyceridemic waist is present in hypertensive patients with a normal FPG level as well as moderate hyperglycemia (a FPG level 110-125 mg/dL) with obesity in those with impaired fasting glucose.