Background: The global burden of diabetes and hypertension has grown substantially in recent decades, making them leading causes of illness and death worldwide. Central obesity indicators such as waist circumference (WC) and waist-to-hip ratio (WHR) have shown a strong association with increased risk of these conditions. Although body mass index (BMI) is widely used to measure obesity, evidence suggests that WC and WHR may serve as more reliable predictors for the development of diabetes and hypertension. A clearer understanding of these relationships can enhance risk assessment and support the design of targeted public health interventions. Aim and objectives: This study was aimed to assess the association between diabetes mellitus, hypertension, and various anthropometric measures in adults aged 25–70 years. The specific objectives were to measure obesity indicators such as BMI, WC, and WHR among adults with diabetes and/or hypertension and assess the individual risk association of these indices with diabetes and hypertension. Materials and methods: A cross-sectional study was conducted in the Medicine Outpatient Department (OPD) of Government Cuddalore Medical College and Hospital, involving 100 participants aged 25–70 years from both genders. The participants were divided into four groups of 25 each: normotensive diabetics, hypertensive nondiabetics, hypertensive diabetics, and normotensive nondiabetics. Anthropometric measurements such as weight, height, BMI, WC, and WHR were recorded, along with random blood sugar (RBS) and blood pressure levels. Data were analyzed using analysis of variance (ANOVA) in SPSS software. Results: Most participants were aged between 41 and 50 years, with a female preponderance. The mean BMI was significantly higher (p < 0.05) in the groups with diabetes, hypertension, and both conditions, compared with the group without either condition. Additionally, the mean WC and WHR were significantly higher (p < 0.05) in the group with both diabetes and hypertension than in the group without these conditions. Conclusion: Central obesity measures such as BMI, WC, and WHR are strongly associated with diabetes and hypertension, underscoring their significance in risk assessment and targeted public health interventions.