Diabetes, Vol 24, Issue 9 820-828, Copyright © 1975 by American Diabetes Association
Age-adjusted analysis of insulin responses during normal and abnormal glucose tolerance tests in children and adolescents
AL Rosenbloom, L Wheeler, R Bianchi, FT Chin, CM Tiwary and A Grgic
This report analyzes age-specific glucose (PG) and immunoassayable insulin
(IRI) responses during oral glucose tolerance testing (OGTT) and examines
test results in children and adolescents with OGTT abnormality using the
age-appropriate control data. Controls' (n = 93) and patients' (n = 63)
results were compared on the basis of statural age (SA) at the time of
testing. Control tests (n = 101) showed significant positive correlation of
fasting and four-hour postingestion PG with SA (p less than 0.001), but
mean area under the PG curves did not vary between the SA groups (I--18.69
months, II--70-131 months, III--132+ months). The absence of differences of
other sampling times permits uniform diagnostic criteria for this age
group. IRI was positively correlated with SA at all testing times, and mean
levels differed significantly between each SA group at every sampling time;
the mean areas under the IRI curve also differed significantly between SA
groups as did the mean ratios of IRI area to PG area (group I--0.2639 +/-
0.0175 S.E.M., group II--0.3864 +/- 0.0235, group III--0.6262 +/-0.0491).
Patient tests (n = 110) were separated into normal (N), borderline (B), and
chemical-diabetic (C) for each SA group. IRI means were above control data
for each test type in each SA group at all sampling times; one fourth of
these differences were significant. IRI responses also increased within
each SA group from N to B to C tests. Mean IRI areas and IRI area to PG are
mean ratios were higher than in controls, and this difference was greatest
with the most abnormal (C) test type in each SA group. A subgroup of three
patients who had low IRI responses from the outset and developed overt
diabetes in one to three years was excluded from the analysis. In contrast
to apparent relative insulin inefficiency with normal maturation and with
chemical diabetes, they had exceptional responsiveness to their low IRI
levels. Variable involvement of alpha as well as beta cells in the
pathophysiology of diabetes is suggested as one explanation for these
paradoxic observations. Changing receptor affinity might also be
implicated.