Objective: C peptide measurement can be helpful for classification of diabetes mellitus (DM). The aim of this study was to investigate the association between clinical diagnosis of type 1 diabetes (T1D) and levels of random C peptide.
Methods: Random C peptide was measured in adults of multi-ethnic background who had been classified as having T1D according to their clinical presentation. All individuals were > 18 years old at onset.
Results: The study included 51 adults, 28 (54.9%) females and 23 (45.1%) males, 36 (70.6%) Caucasian and 15 (29.4%) non-Caucasian. Their mean age at onset and duration of DM mean age were 27.9 (+/- 7.5) years and 9.9 (+/-7.2) years, respectively. In 8 patients (15.7%) C peptide was > 1.5 ng/ml, indicating sustained beta cell function. In this group a higher level of body mass index (26.05 vs 23.05 kg/m(2); p=0.006) and a greater proportion of non Caucasian individuals (62.5% vs 23.3%; p=0.039)) were detected.
Conclusion: Most patients with DM clinically classified as T1D exhibit low C peptide. However, pancreatic insulin secretion seems to be preserved in a significant proportion of those individuals, possibly representing an atypical form of DM, not yet elucidated, that combines characteristics of both T1D and T2D.