Serum insulin, IGF-I, IGF-II and growth hormone, and left ventricular mass in noninsulin-dependent diabetes mellitus

OBJECTIVE: To investigate whether serum insulin, insulin-like-growth factor I (IGF-I), insulin-like-growth factor II (IGF-II) and growth hormone (GH) - each of which is a known trophic factor in vitro for the cardiomyocyte, and levels of which can be altered in noninsulin-dependent diabetes mellitus (NIDDM)- are related to left ventricular (LV) mass in patients with NIDDM. DESIGN: Observational study. SETTING: University teaching hospital. PATIENTS AND METHODS: Patients with NIDDM without signs, symptoms or past history of hypertension, ischemic or valvular heart disease, or heart failure were recruited from the diabetes clinic of university hospital. Fasting patients had blood drawn for determination of serum insulin, IGF-I, IGF-II and GH by radioimmunoassay. Height, weight and blood pressures were recorded. An electrocardiogram was obtained and echocardiography was performed for calculation of LV mass. RESULTS: Patients' average age was 54.7+/-1.6 years, and duration of NIDDM was 9.3+/-1.2 years. LV mass was 113.7+/-8.9 g/m(2) in men (n = 13) and 104.1+/-10.8 g/m(2) in women (n = 10). Serum insulin was 25.3+/-1.8 ng/ml, IGF-I was 255+/-15 ng/mL, IGF-II was 0.62+/-0.05 mu g/L and GH was 5.4+/-0.5 ng/mL. There were no significant differences in LV mass among patients with serum insulin, IGF-I, IGF-II or GH in the upper compared with the lower 50 th percentile. There were no significant differences in serum insulin, IGF-I, IGF II or GH among patients in the upper compared with the lower 50th percentile fur LV mass. Standardization of LV mass for body size, either by height or body surface area, did not alter the relationships. The correlation coefficients from linear least squares regression analysis between these hormones and LV mass were low (r<0.003), suggesting that even much larger sample sizes might not alter these findings. CONCLUSIONS: These data suggest that circulating total serum concentrations of growth factors (insulin, IGF-I, IGF-II and GH) are not determinants of LV mass in nonhypertensive patients with NIDDM.