Objectives/aims. To determine the prevalence of diabetes mellitus treated with drugs and the prescription of drugs in diabetes (oral anti-diabetics and insulin) in the Community of Madrid between 1996-2002. Methods. We used the indirect method for estimating the rate of prevalence of diabetes based on antidiabetic drug in the Madrid Community. We studied the consumption or oral antidiabetics (OH) and insulin (IN) in all the Madrid Community Area from 1996 to 2002. To make consumption uniform we used the daily doses/1,000 inhabitants/ day (DHD). The total consumption was obtained using the official billing data and the annual population data provided by the «Institute Madrileño de Salud». Results. The prevalence of diabetes mellitus increased 62.5% in the period studied, ranging from 1.6% in 1996 up to 2.6% in 2002. The DHD of oral drugs increased 87.8% from 12.2 in 1996 to 23.07 in 2002. The DHD of insulin decreased 28.2% from 3.99 in 1996 down to 3.11 in 2002. The OH/IN ratio increased 138%, from 3.11 to 7.42 in 2002. There is a tendency to increase biguanide and sulfonilureas with low risk of hypoglycemia. The total cost of insulin and oral medication increase every year, the increase of diabetic patients and the cost/DDD of the new drugs are factors that increase the total cost of diabetes. Conclusions. The prevalence of diabetes mellitus treated with drugs increased in the Community of Madrid. There is a progressive use of oral drugs versus insulin, and a tendency to prescribe biguanide, sulfonylureas, especially gliclazide and glimepiride. A tendency to substitute insulin with insulin analogues is also seen in the use of insulin. The cost of diabetes increases yearly.