title: Discriminative capacity of fasting C-peptide levels in a functional test according to different criteria of response to a stimulus. A study of Brazilian insulin-dependent diabetic patients.
abstract: In order to study the discriminative capacity of the C-peptide basal values (BV) in a functional test, we analysed the C-peptide response curve after a mixed meal in 26 insulin-dependent patients. The five criteria of response used were: (1) any increment after the stimulus; (2) percentual increment above 21%; (3) absolute increment above 0.35 ng/ml; (4) incremental area above 42.76 ng.min.ml-1, and (5) peak value above 2.16 ng/ml. Considering the first two criteria, many patients showed positive responses, in the diabetic group as a whole and when we analysed patients with BV > or = 0.74 ng/ml and < 0.74 ng/ml separately. When we applied only the last three criteria the number of positive responses was considerably smaller. Moreover, the majority of patients with BV < 0.74 ng/ml could not increase their levels over the ones established above. In patients with BV > or = 0.74 ng/ml, the number of positive and negative responses were similar. The comparison between the subgroups achieves statistical significance only for incremental area (chi 2 = 3.55, p = 0.03). We conclude that the functional test was important mainly for patients with BV > or = 0.74 ng/ml, and could have been omitted for patients with BV < 0.74 ng/ml. The best criteria of response were those based on the mean minus two standard deviations of each parameter in a non-diabetic group (the last three criteria), especially the incremental area.
authors.affiliation: State University of Rio de Janeiro, Department of Internal Medicine, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Pozzan
authors.forename: T
authors.initials: T
authors.lastname: Dimetz
authors.forename: H M
authors.initials: HM
authors.lastname: Gazolla
authors.forename: M B
authors.initials: MB
authors.lastname: Gomes
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D001938:Brazil; D002096:C-Peptide / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D004435:Eating; D005215:Fasting; D005260:Female; D006801:Humans; D007328:Insulin / Q000627:therapeutic use; D007515:Islets of Langerhans / Q000378:metabolism; D008297:Male
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin