C-Peptide Exerts Beneficial Effects on Myocardial Blood Flow and Function in Patients With Type 1 Diabetes

Myocardial dysfunction, perfusion abnormalities, and the extent to which these abnormalities may be reversed by C-peptide administration was assessed in type 1 diabetic patients. Eight patients were studied before and during a 0.84-mg/kg dipyridamole administration using a randomized double-blind crossover protocol with infusion of C-peptide (6 pmol x kg(-1) x min(-1)) or saline during 60 min on two different days. Myocardial function was measured as peak myocardial velocity during systole (Vs) and early diastole (Vd) by pulsed tissue Doppler imaging. Myocardial contrast echocardiography was used for assessment of myocardial blood volume (SI(max)) and myocardial blood flow index (MBFI) calculated from the relation between trigger interval and signal intensity. Eight age-matched healthy volunteers served as control subjects. In the basal state, Vd (13.8 +/- 0.6 vs. 15.6 +/- 0.5 cm/s, P < 0.04) and SI(max) (6.6 +/- 0.6 vs. 8.2 +/- 0.6 a.u. P < 0.04) were reduced in patients compared with control subjects. Dipyridamole administration significantly increased indexes of myocardial function and blood flow to a similar extent in patients and control subjects. During C-peptide administration, Vs and Vd increased by 12% (P = 0.03), SI(max) increased from 6.6 +/- 0.6 to 8.1 +/- 0.7 a.u. (P < 0.02), and MBFI increased from 3.3 +/- 0.4 to 5.3 +/- 0.9 (P < 0.05). The results demonstrate that type 1 diabetic patients have impaired myocardial function and perfusion in the basal state that can be improved by short-term replacement of C-peptide.