Concordance between fasting and 2-h post-glucose challenge criteria for the diagnosis of diabetes mellitus and glucose intolerance in high risk individuals

Aims To compare the new fasting with the 2-h post glucose challenge diagnostic criteria for diabetes mellitus in a high-risk Central European population. Methods The results of the 75-g oral glucose tolerance tests (OGTT) performed between Ist January 1990 and 31st December 1998 in patients at high risk of glucose metabolism disturbance were analysed. Results From 1554 patients with OGTT results available for the study, 1360 (759 women and 601 men, aged 65.5 +/- 6.9 years, body mass index 28.2 +/- 4.5 kg/m(2)) were included into the study. With the use of the post challenge criteria, 41.3% of the analysed population had diabetes or impaired diabetes tolerance (IGT), whereas with the new fasting system only 16.6% would have been be diagnosed with any type of glucose intolerance. Diabetes was significantly more often diagnosed with the post-challenge criteria than with the fasting ones: 16.2 vs. 5.3% (P < 0.0001). The subjects with diabetes diagnosed upon fasting glucose value were significantly younger than the subjects with diabetes diagnosed according to the 2-h glucose challenge: 65.7 +/- 6.2 vs. 68.8 +/- 7.0 years, respectively (P < 0.01). The sensitivity of the new criteria for the diagnosis of diabetes was 18.2%, and specificity 97.2%. A total of 77.8% of IGT cases would have been diagnosed as having normal glucose metabolism according to the fasting glucose. The sensitivity of the new criteria for the diagnosis of impaired glucose tolerance (IGT or impaired fasting glucose) was 14.6%, and specificity 89.8%. The overall kappa statistic (kappa) was low: 0.211 (95% confidence interval 0.149-0.27). Conclusions The new lower fasting criteria might be too insensitive to identify a large proportion of individuals with diabetes or impaired glucose intolerance, particularly in a high-risk population.