Akademik Veri Yönetim Sistemi
DIABETOLOGIA, cilt.48, sa.1, ss.640, 2005 (SCI-Expanded)
Dynamic testing of growth hormone/insulin-like growth factor-1 axis in type 2 diabetes mellitus
S. Dagdelen, O. Gedik; Endocrinology, Hacettepe University, School of Medicine, Ankara, Turkey.
Background and Aims: Growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis contributes mitogenic, atherogenic and proliferative process of the body. Hypopituitarism associated with diabetes mellitus (DM) was defined to have a protective role against proliferative complications of DM. Evenly, pituitary radiotherapy was offered by some authors in the past, as a therapeutic option for proliferative retinopathy. We aimed to investigate GH/IGF-1 axis in type 2 DM in a cross-sectional case-control study.
Materials and Methods: Fourty-six type 2 diabetic cases (M/F: %58, age: 55.5 ± 10.6 yrs, BMI: 30.8 ± 7.2 kg/m2, disease duration: 4.82 ± 4.73 yrs, HbA1c: % 7.4 ± 1.5, FPG: 167.7 ± 59.6 mg/dl, PPG: 208.9 ± 97.4 mg/dl) were matched with 28 healthy controls according to age, sex, and body-massindex. Patients with proliferative complications were excluded. Overnight fasting samples were obtained for basal GH and IGF-1 levels. The day after, IGF-1 generation test was performed with single dose injection of GH 0.1 mg, s.c., at 08 00 am. Response to exogenous GH was evaluated via IGF1 assays at 24th hour of injection [∆IGF-1= (Stimulated IGF-1) - (Basal IGF-1)]. Results: Basal GH (0.28 ± 0.24 ng/ml vs 0.49 ± 0.52 ng/ml) and IGF-1 (207.8 ± 102.0 mcg/l vs 278.9 ± 131.6 mcg/l) levels were significantly lower in patients with type 2 DM, compared to controls, (p values: 0.017 vs 0.011, respectively). Stimulated IGF-1 levels (377.3 ± 143.9 mcg/l vs 487.6 ± 135.4 mcg/l, respectively in cases and controls) were also lower in type 2 DM (∆IGF-1: 166.8 ± 63.6 mcg/l) than controls (∆IGF-1: 208.7 ± 41.4 mcg/l), (p=0.002). Patients with poor glycemic control (HbA1C > % 8.5) tended to give a lower response to IGF-1 generation test (∆IGF-1: 144.5 ± 67.5 mcg/l) than the patients (HbA1C < %7.0) with good glycemic control (∆IGF-1: 180.3 ± 66.4 mcg/l), but the difference did not reach statistical level of significance (p=0.187). In contrast, presence of current insulin therapy (122.5 ± 53.3 mcg/l vs 180.6 ± 60.8 mcg/l) and micro- (115.6 ± 51.7 mcg/l vs 180.7 ± 59.8 mcg/l) or macrovascular (135.5 ± 65.6 mcg/l vs 180.8 ± 58.5 mcg/l) complications were associated with decreased ∆IGF-1 levels at a statistically significant level (p values: 0.01, 0.006, and 0.008 respectively), compared to lack of each conditions respectively.
Conclusion: Our study suggests that, type 2 DM is associated with a decrease in basal and stimulated IGF-1 levels. Ongoing exogenous insulin therapy and presence of micro- or macrovascular complications display a further decrease in the IGF-1 response to exogenous GH administration, but glycemic control do not. Implications of our findings on the glycemiccontrol independent complications of diabetes require further clinical trials.