OBJECTIVES: In the long term there is a high rate of sulphonylurea (SU) prescription on oral antidiabetics (OAD) in Slovakia compared to DM treatment standards in other countries. Although this rate is decreasing slowly, there is a need to force the prescription habits improvement in diabetic patients. Our objective was to use collected data and analyse prescription habits of diabetologists with a focus on SU and biguanides rate. METHODS: We used claims data of reimbursed medicines in 2005 of one Slovak health insurance fund. Diabetic patient was identified as the one with at least two prescriptions regarding DM diagnosis on annual basis. SU rate compared to the total SU and metformin prescription was calculated for each diabetologist on the basis of expenditure in DDDs. RESULTS: We identified 13,481 diabetics (7% of total DM patients undergoing pharmacotherapy in Slovakia). These patients were treated by 212 diabetologists. Average SU verus biguanides rate was 59%. Worldwide, this rate stands for approximately 40%. This difference requires further steps so the doctors were categorized in deciles for purposes of targeted audit. Furthermore, we calculated the savings if patients would go to biguanides instead of SU. CONCLUSION: Claims data are an effective tool for auditing of prescription habits. Our study confirmed the difference in prescription habits and results should be disclosed to prescribers. Mutual co-operation of health insurance and specialists on similar analyses and quality indexes specifications has a great potential to change the treatment patterns and could lead to significant savings when followed by direct feedback and education.