Objective: To compare the degree of concordance between plasma and capillary glucose for screening of diabetes mellitus in adolescents.
Methods: The plasma and capillary glucose of 119 adolescents aged 10-19 yr (36 males and 83 females) from public schools in Niterói, Rio de Janeiro State, Brazil, were verified after a 12-h fast. Agreement was assessed through kappa statistics (k), McNemar's chi-squared test, and the intraclass correlation coefficient (ICC). The paired Student's t-test for comparison of means, the approaches by Altman and Bland, and the survival-agreement plot were also applied.
Results: Mean values of plasma glucose were 7.9 points higher than the capillary values (91.5 vs. 83.6 mg/dL, p < 0.001; ICC = 0.419). A regular agreement between the methods (k = 0.31, p < 0.001) for assessing proportions of adolescents with glycemia > or =100 mg/dL is observed. Using the strategy of adding 8 mg/dL to the capillary levels, the agreement improved (k = 0.46, p < 0.001) and a significant difference was not observed between the estimated prevalences (p = 0.815).
Conclusions: The results suggest a satisfactory agreement between the two methods when capillary glucose is corrected, and this may be a useful and low-cost tool for the epidemiologic investigation of diabetes mellitus prevalence in adolescents.