RAPID DECREASE OF FASTING C PEPTIDE LEVELS AFTER DIAGNOSIS OF TYPE 1 DIABETES MELLITUS

Abstract

Introduction. Type 1 diabetes mellitus (T1DM) is characterized by absolute insulin deficiency. Fasting C peptide is a marker of endogenous insulin secretion. Small amounts of C peptide can be found in the sera of patients with T1DM at disease onset, but its concentration decreases thereafter. The purposes of this study were to evaluate, regarding endogenous insulin secretion, a group of T1DM patients from Romania, and to estimate the time trends of fasting C peptide.

Methods. T1DM patients (n=260), 15.1±4.7 years of age (range 3.7-27.7 years), 135 male (51.9%), were recruited from Clinical Medical Center “Cristian ùerban”, Buziaú. Mean±SD diabetes duration was 2.1±2 years (range 0.1-15.7 years). Fasting C peptide was measured by immuno-enzymatic assay. The results were expressed as ng/ml. The normal range for fasting C peptide was defined by 5th and 95th percentiles from a control group (n=97), matched for age and sex: 0.57-4.44 ng/ml. The study group was divided, according to T1DM duration, into 5 subgroups: 0-6 months (n=47), 6-12 months (n=45), 1-2 years (n=70), 2-3 years (n=43) and >3 years (n=55).

Results. Mean±SD value for fasting C peptide was 0.34±0.56 ng/ml (range 0-3.09 ng/ml). The values, according to T1DM duration, were: 0.54±0.71 ng/ml (range 0- 3,09 ng/ml) (0-6 months); 0.32±0,35 ng/ml (range 0.01-1.51 ng/ml) (6-12 months); 0.27±0.48 ng/ml (range 0-3.05 ng/ml) (1-2 years); 0.28±0.52 ng/ml (range 0-2.18 ng/ml) (2-3 years); 0.33±0.66 ng/ml (range 0-2.79 ng/ml) (>3 years). The difference between fasting C peptide in patients with disease duration 0-6 months and the rest was statistic significant (0.54±0.71 ng/ml versus 0.3±0.51 ng/ml, p=0.03).

Conclusions. Fasting C peptide decreases abruptly 6 months after T1DM onset and registers quite constant values thereafter. Consequently, a preventive method for T1DM, should it exist, has to be applied in the first 6 months after diagnosis.