OBJECTIVES: The increasing prevalence of overweight and obesity in US means increasing cost of treating cardiovascular and other life threatening diseases. This is particularly relevant to people with type 2 diabetes (T2D) of whom over 80% are overweight or obese. Limited data exist on the impact of overweight and obesity on health care cost for the people with T2D. The objective was to identify the relations between health care cost and BMI for people with T2D. METHODS: Generalised Linear Models (GLM) were performed linking demographic variables (age, gender, ethnicity, BMI, HbA1c) and annual cost of medical resources (drugs, hospitalisation and visits to health professionals (PCP's, cardiologist, diabetes specialist, diabetes nurse, other doctor/nurse)). Data was based on 643 patients diagnosed with T2D, aged between 35 to 64 years and a BMI= 20 kg/m2 (based on physician reported height and weight) from the Adelphi Metabolic Syndrome Disease Specific Programme in 2006. People were stratified according to their BMI; normal/overweight (20-29.99 kg/m2; n=110), obese (30-34.99 kg/m2; n=178); very obese (35-39.99 kg/m2; n=170) and morbidly obese (>39.99 kg/m2; n=185). RESULTS: The GLM analyses showed a significant impact on health care cost determined by age, BMI and HbA1c. This means that the major significant contributors to the short term health care cost of type 2 diabetes are the people's age, BMI group and HbA1c level. Compared with a BMI between 20-29.99 kg/m2 moving to the BMI group 30-34.99 kg/m2, 35-39.99 kg/m2, and >39.99 kg/m2 results in an increase in cost of $363 (p=0.06), $553.7 (p<0.05), and $674.4 (p<0.05) per year, respectively. CONCLUSION: These findings suggest that health care costs of type 2 diabetics are positively correlated with age, BMI and HbA1c level. The impact of obesity on health care cost is particularly evident in people with T2D in the high obesity groups.