Identification of hypertensive patients with pre-diabetes or diabetes is important for timely prevention of complications including vascular disease. We aimed to compare the association and discrimination of central obesity measures (waist circumference [WC] and waist-to-height ratio [WHtR]) with generalized obesity measure (body mass index [BMI]) in relation to pre-diabetes and diabetes among a group of Asian hypertensive patients for the first time. We used the baseline data of 925 subjects aged 40 years or older with uncontrolled hypertension recruited at eight primary care clinics in Singapore. Information on height, weight, WC, fasting blood glucose, and hemoglobin A1c (HbA1c) was collected. Pre-diabetes or diabetes was defined as having reported physician-diagnosed diabetes or taking anti-diabetes medication, fasting blood glucose ≥ 5.6 mmol/dL or HbA1c ≥ 5.7%. Among 925 subjects, 495 (53.5%) had pre-diabetes or diabetes. In logistic regression models, BMI was not associated with pre-diabetes or diabetes after adjusting for WC or WHtR, while a positive association remained with both WC and WHtR after adjustment of BMI. Both WC and WHtR had significantly better discrimination than BMI (respective area under ROC curve: 0.63 for WC, 0.63 for WHtR, and 0.60 for BMI; P = 0.019), and adding WC or WHtR on top of BMI further correctly reclassified 42.7% and 38.7% hypertensive patients to the right risk group of pre-diabetes or diabetes indicated by net reclassification improvement. However, WHtR was not superior to WC. In conclusion, our results suggested that central obesity has stronger association with and better discrimination for pre-diabetes or diabetes than generalized obesity.