Evaluation of WHO and NDDG criteria for impaired glucose tolerance.

A 4-year prospective study on the natural history of IGT in South African Indians has allowed for the evaluation of the WHO and NDDG criteria for IGT, using the five groups for non-diabetic glucose tolerance recently recommended and relating these to the risk of diabetes development. Using WHO criteria, 128 subjects were classed IGT in a baseline survey (Year 0). The five recommended categories were applied to the OGTTs done between Year 1 and Year 4 of the study, when mid-test plasma (MPG) samples were also obtained. These categories included N-N (Normal by WHO and NDDG); N-ND1 (Normal by WHO, non-diagnostic level 1 by NDDG); N-ND2 (Normal by WHO, non-diagnostic level 2 by NDDG); I-ND3 (IGT by WHO, non-diagnostic level 3 by NDDG) and I-I (IGT by WHO and NDDG). The risk of diabetes development and the significance of the non-diagnostic category were evaluated by comparing the glucose tolerance status at Year 4 with the status at Year 1. In the cross-sectional evaluation at Year 1, of the 87 non-diabetic OGTTs analysed, 31% (n = 27) were classified I-I, 34.5% (n = 30) were classed N-N and 34.5% (n = 30) were classified non-diagnostic [I-ND3 (23.1%); N-ND2 (8%); N-ND1 (3.4%)]. In the prospective analysis, of the 72 subjects who completed the study, 16 subjects developed NIDDM by Year 4; of these 13 subjects were classed I-I and 3 subjects I-ND3 at Year 1.(ABSTRACT TRUNCATED AT 250 WORDS)