Patients with type 1 diabetes (T1D) may exhibit some residual insulin secretion for many years after their diagnosis. This has been associated with a more favorable prognosis. OBJECTIVE: To analyze insulin secretion in individuals with T1D using C-peptide (CP) response to glucagon and comparing patients with recent onset (<5 years - Group 1) and long-standing disease (>5 years -Group 2). METHODS: Subjects with T1D had their blood sampled before (fasting) and 6 minutes after glucagon infusion for CP, HbA1c and anti-GAD measurement. RESULTS: Forty-three individuals were evaluated, 22 in Group 1 and 21 in Group 2. Preserved insulin secretion (CP >1.5 ng/mL) was observed in 6 (13.9%) and in 8 (18.6%) patients before (CP 1) and after (CP 2) glucagon stimulus, respectively, showing no difference between the groups (p=0.18 and 0.24). CP 1 and CP 2 were detectable (>0.5 ng/dL) in 13 (30.2%) and 18 (41.9%) patients, respectively. Both were more frequent in Group 1 than in Group 2 (p=0.45 for CP1/p=0.001 for CP 2). Similar serum levels where seen between the groups, both before and after stimulus (1.4±0.8 vs. 1.2±1.0; p=0.69 and 1.8±1.5 vs. 1.7±0.8; p=0.91). Group 1 presented an inverse correlation between disease duration and CP 2 (R=-0.58; p=0.025). CONCLUSION: A significant number of patients with T1D have detectable residual insulin secretion, especially in the first 5 years of disease. These subjects are an ideal population for clinical trials that target the prevention of β cell function loss in T1D.
Type 1 diabetes; C-peptide; insulin secretion; disease duration
