The C-peptide response to a standard mixed meal in a group of Brazilian type 1 diabetic patients.
In order to analyze the different parameters used in the interpretation of C-peptide response in a functional test, we compared a group of 26 type 1 diabetics aged 21.1 +/- 8.2 years, with a diabetes duration of 7.9 +/- 6.7 months, with a group of 24 non-diabetic subjects aged 25.0 +/- 4.4 years. A standard mixed meal of 317 kcal was used as a stimulus. Blood sampling for C-peptide determinations was performed at regular intervals. Although all the studied C-peptide variables were significantly lower in the diabetic group (P < 0.0001), some overlapping of parameters was observed between the two groups. The highest degree of overlapping was found for basal value (BV) (30.8%) and percent increase (42.31%), and the lowest for incremental area, absolute increase, peak value (PV) (3.8%), and total area (7.7%) (chi 2 = 31.6, P < 0.0001). We did not observe a definite pattern in the time of maximum response among the 21 diabetics who showed an increase in C-peptide levels after the stimulus. In this group, however, there was a highly significant number of late responses (120 min) (chi 2 = 5.7, P < 0.002). Although BV showed a significant correlation with PV (rS = 0.95, P < 0.0001), the basal levels of C-peptide did not differentiate the groups with and without response to the stimulus. We conclude that the diabetic group studied showed delayed and reduced C-peptide responses, and that the functional test can be an important tool for the evaluation of residual beta cell function.
Pozzan
R
R
Departamento de Medicina Interna, Universidade do Estado do Rio de Janeiro, Brasil. pozzan@urbi.com.br
Dimetz
T
T
Gazzola
H M
HM
Gomes
M B
MB
D000293:Adolescent; D000328:Adult; D001938:Brazil; D002096:C-Peptide / Q000097:blood*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D004435:Eating; D005260:Female; D006801:Humans; D008297:Male
D002096:C-Peptide