Because of adverse metabolic effect, thiazide diuretics (T) are usually used as low dose combinations in antihypertensive therapy. We sought to investigate glucometabolic abnormality in hypertensive patients with (T+) and without low dose thiazide diuretics (T-) as combination therapy. We prospectively enrolled 702 hypertensive patients (age, 57.7±10.3 years; T+, 188) without known diabetes, atherosclerotic cardiovascular disease, heart failure, and renal failure. Patients’ antihypertensive regimens had not been changed for at least 6 months at the time of enrollment. Fasting lipids, fasting plasma glucose (FPG), and 2 h plasma glucose (2 h PG) after ingestion of a 75 g glucose load were measured. There were no significant differences in age, sex distribution, body mass index, and lipid profiles between the T+ and T- groups. Proportions of patients with old generation β-blockers, calcium antagonists, and ACEI/ARB were not different. Use of statins was lower in T+ group (32.4 vs 41.2%, p<0.05). FPG was similar (106.1±13.0 vs 104.4±13.1 mg/dL, p=NS), but 2 h PG was higher in T+ group (148.1±53.6 vs 139.3±49.2 mg/dL, p<0.05). In patients with FPG <100 mg/dL, prevalence of post-load hyperglycemia (2 h PG ≥140 mg/dL) was higher in T+ group (33.3 vs 20.0%, p<0.05). Linear regression analysis revealed that T+ was independently associated with post-load hyperglycemia (B=0.137, SE=0.067, p=0.04). In patients with FPG 100-125 mg/dL, diabetes by 2 h PG criteria was not different between the two groups (17.2 vs 10.8%, p=NS). Post-load hyperglycemia is increased with T+, even though FPG is <100 mg/dL, This should be considered during follow-up of hypertensive patients.