Type I diabetes manifested solely by 2-h oral glucose tolerance test criteria.
The clinical presentation of type 1 diabetes usually involves symptoms such as polyuria and polydipsia. However, investigators in the Diabetes Prevention Trial of Type 1 Diabetes (DPT-1) have detected a group of subjects with type 1 diabetes who have a different phenotype. These subjects are asymptomatic, have normal (<6.1 mmol/l) (group A) or impaired (6.1- <7.0 mmol/l) (group B) fasting glucose, but have 2-h glucose values >11.1 mmol/l on their oral glucose tolerance tests (OGTT). Of the 585 OGTTs performed on islet cell antibody (ICA)-positive relatives with insulin autoantibodies (IAA) or low first-phase insulin response (FPIR), normal glucose tolerance (NGT) was found in 427 subjects; impaired glucose tolerance (IGT) was found in 87 subjects, and diabetes was found by 2-h OGTT criteria alone in 61 subjects. Despite marked differences in 2-h glucose values (NGT 5.8 +/- 1.1 mmol/l, IGT 8.9 +/- 0.9 mmol/l, and group A 13.5 +/- 2.5 mmol/l), there were no significant differences in fasting glucose values among NGT (4.8 +/- 0.5 mmol/l), IGT (5.03 +/- 0.5 mmol/l), and group A (4.99 +/- 0.7 mmol/l) categories. Mean FPIR was higher in subjects with NGT compared with subjects with IGT and subjects diagnosed by 2-h OGTT criteria alone. However, the correlation between FPIR and 2-h glucose value was low (r2 = 0.114). Multivariate analysis demonstrated that additional independent variables provide smaller contributions to the 2-h glucose value. In conclusion, there are asymptomatic type 1 diabetic subjects whose diabetes was diagnosed by the 2-h criteria on OGTT alone. Despite the importance of beta-cell dysfunction in the pathogenesis of type I diabetes, factors other than impaired FPIR must also contribute to postprandial glucose tolerance in these subjects.
Department of Veterans Affairs, Puget Sound Health Care System and the Department of Medicine, University of Washington, Seattle, USA. cjgreen@vmresearh.org
C J
CJ
Greenbaum
D
D
Cuthbertson
J P
JP
Krischer
D000293:Adolescent; D000328:Adult; D000906:Antibodies / Q000032:analysis; D001786:Blood Glucose / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D005260:Female; D018149:Glucose Intolerance / Q000175:diagnosis / Q000209:etiology; D005951:Glucose Tolerance Test; D006239:Haplotypes; D006801:Humans; D007223:Infant; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D012016:Reference Values; D013997:Time Factors
D000906:Antibodies; D001786:Blood Glucose; D007328:Insulin