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.
Greenbaum
C J
CJ
Department of Veterans Affairs, Puget Sound Health Care System and the Department of Medicine, University of Washington, Seattle, USA. cjgreen@vmresearh.org
Cuthbertson
D
D
Krischer
J P
JP
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