Circulating IGF-I concentrations are low and not correlated to glycaemic control in adults with type 1 diabetes

Abstract

Objective: To study plasma concentrations of insulin-like growth factor-I (IGF-I) in adults with type 1 diabetes (IDDM) in comparison with a reference population, and the in¯uence of glycaemic control, dose of insulin, and sex on the concentration of circulating IGF-I in IDDM. Design and methods: Patients with type 1 diabetes were recruited consecutively from our outpatient diabetes unit. In all, 79 men and 55 women aged 20±60 years with a disease duration $6 years (range 6±51 years) took part in the study. A reference population of 80 men and 83 women aged 20±60 years was randomly obtained from the population registry. IGF-I was measured with radioimmunoassay after acid±ethanol extraction.

Insulin-like growth factor I receptors are more abundant than insulin receptors in human micro- and macrovascular endothelial cells

“…With regard to the prevalence of IGF-IR in human endothelial cells, it is of great interest that several conditions with low circulatory IGF-I are associated with vascular disease. IGF-I levels are low in type 1 diabetes mellitus, probably due to insufficient insulinization of the liver (11,15). In normal aging, IGF-I levels decrease with increasing age throughout adulthood (24,28).…”

Expression and function of receptors for insulin-like growth factor-I and insulin in human coronary artery smooth muscle cells

“…In spite of activation of IR β-subunit at an insulin concentration of 10 −9 mol/l, insulin at 10 −9 -10 Speculating on the consequence, if HCASMCs respond to IGF-IR or hybrid IR/IGF-IR, we would point out that there are several conditions in which low circulating IGF-I is associated with different vascular diseases. These conditions include type 1 diabetes mellitus [46,47], growth hormone deficiency [48,49] and normal ageing [50]. An increasing prevalence of vascular diseases and low IGF-I levels has been reported in epidemiological studies [4].…”

Short-term effects of NPH insulin, insulin detemir, and insulin glargine on the GH–IGF1–IGFBP axis in patients with type 1 diabetes

“…Correspondingly, serum total IGF1 levels revealed minor but significant reductions (Fig. 1D) with the treatment of NPH insulin, insulin detemir, and insulin glargine (7,8, and 10% respectively; all P values !0.05) during the 0-6 h period.…”

“…These abnormalities are consequences of portal insulinopenia and include GH hypersecretion, secondary to low circulating levels of IGF1 and elevated levels of IGFBP1 (7,8,9). Although these abnormalities to a certain extent reflect the glycemic control (10), they are likely to be metabolically unfavorable per se.…”

“…GH exerts insulin-antagonizing effects whereas IGF1 serves as an insulin sensitizer (11,12). Tight glycemic control appears, however, to be unable to fully normalize the changes of the GH-IGF1-IGFBP axis (8). This may be explained by the inability to normalize portal insulin levels following s.c. insulin administration (13).…”