[Quantitative approach to drug compliance of diabetics]

Many patients do not take their medication according to the instructions of their physician. Patient compliance is particularly poor in the long-term treatment of diseases, which produce only minor symptoms in the patient. The aim of the present study was to quantitate patient compliance in diabetics treated with tolbutamide. The amount of tolbutamide taken by the patient was estimated on the basis of its 24 hours urinary excretion. The collection of the 24 hours urine is a standard procedure in our outpatient clinic for the measurement of glycosuria. The study involved 33 diabetics followed over several months. In those reliable patients, who conscientiously took their medication, we found a good correlation between the prescribed dose and the 24 hours urinary excretion. In contrast, when the data from the entire group of 33 out-patients was evaluated, the correlation between these two parameters of prescribed dose and urinary excretion was poor. The correlation between urinary excretion and the dose admitted by the patient was just as poor. According to our results, only one out of two diabetics took the prescribed dose. After our initial observations, we informed the outpatients about their inclusion in this study. In spite of the fact that the patients knew that they were under observation for compliance, we found large interindividual differences in the urinary excretion of tolbutamide over several months. In contrast, the intraindividual variability was low. We found that interviews with patients are a poor means to detect non-compliance, whereas urinary excretion measurements appear to be more reliable.(ABSTRACT TRUNCATED AT 250 WORDS)