Diminished levels of insulin-like growth factor-1 may be a risk factor for peripheral neuropathy in type 2 diabetes patients.

ABSTRACT

AIMS/INTRODUCTION: To investigate risk factors for diabetic peripheral neuropathy (DPN) and to explore the connection between insulin-like growth factor-1 (IGF-1) and DPN in individuals with type 2 diabetes. MATERIALS AND METHODS: A total of 790 patients with type 2 diabetes participated in a cross-sectional study, divided into two groups those with DPN (DPN) and those without DPN (non-DPN). Blood samples were taken to measure IGF-1 levels and other biochemical markers. Participants underwent nerve conduction studies and quantitative sensory testing. RESULTS: Patients with DPN exhibited significantly lower levels of IGF-1 compared with non-DPN patients (P < 0.001). IGF-1 was positively correlated with the average amplitude of both motor (P < 0.05) and sensory nerves (P < 0.05), but negatively correlated with the vibration perception threshold (P < 0.05). No significant difference was observed between IGF-1 and nerve conduction velocity (P > 0.05), or the temperature detection threshold (P > 0.05). Multivariate regression analysis identified diabetes duration, HbA1c, and the low levels of IGF-1 as independent risk factors (P < 0.001). Receiver operating characteristic analysis determined that at 8 years duration of diabetes, 8.5% (69.4 mmol/mol) HbA1c and 120 ng/mL IGF-1, the optimal cut-off points, indicated DPN (P < 0.001). CONCLUSIONS: A reduction of IGF-1 in patients with DPN suggests a potential protective role against axon injury in large fiber nerves of type 2 diabetes patients.