Appropriate use of plasma glucose tests for diagnosis of diabetes mellitus in Ibadan, Nigeria

Background Diabetes mellitus is a growing epidemic in Africa. Its diagnosis relies exclusively on laboratory evidence, which differs based on clinical circumstances. Objective The study described the appropriateness of plasma glucose test requests per the American Diabetes Association criteria. Methods We reviewed the plasma glucose test requests received by the chemical pathology laboratory of the University College Hospital, Ibadan, Nigeria between June 2018 and November 2018. The American Diabetes Association diabetes diagnostic criteria were used to define the appropriateness of test requests and determine the potential for ill-informed clinical decisions. Results Four hundred and twenty-three requisition forms were included, with the majority from the medical wards/clinics (72.3%); the most frequent reason for a plasma glucose test was systemic hypertension (28.6%). Fasting plasma glucose was most requested (254; 60.0%). One hundred and sixteen (27.4%) requests were potentially inappropriate, with the 2-h postprandial plasma glucose (2hPPG) test requests (83; 71.6%) being the most inappropriate. The difference in the proportion of inappropriate requests was not statistically significantly between medical or surgical wards/clinics (Odds ratio 1.131, 95% confidence interval 0.709–1.803, p = 0.605). Inappropriate requests in six cases may have triggered inappropriate action. Conclusion A third of the glucose tests requested for querying diabetes mellitus may have been inappropriate. Results of such testing may trigger inappropriate clinical action. To improve the quality of care and for economic reasons, laboratories should have programmes to improve the appropriate use of their services.