RESUMO
Little is known on the possible association between impaired glucose/insulin metabolism, the pattern of IGFBP-1 phosphorylation and the complex formation with other serum proteins. In this study, the concentration, isoform, multimer and complex pattern of IGFBP-1 was compared in healthy persons and patients with type 2 diabetes mellitus or with hypoglycemia. Concentrations of insulin and IGFBP-1 were determined by radioimmunoassay. Metal affinity and immunoaffinity chromatography were used for the separation of molecular forms of IGFBP-1, which were detected by immunoblotting and SELDI. The counter directional change in insulin and IGFBP-1 concentrations, expressed as a factor that takes into consideration the rate of insulin increase and IGFBP-1 decrease after glucose intake was approximately twice more pronounced in patients with diabetes than in healthy and hypoglycemic persons. The alteration in the phosphorylation pattern of IGFBP-1 due to diabetes or hypoglycemia was not observed. IGFBP-1 multimers found in the circulation of patients with diabetes type 2 differed from those detected in the circulation of others: there were 3 molecular forms between 90 and 100 kDa (compared to one in patients with hypoglycemia or 2 in healthy persons), 2 of which were α (2)M-reactive and one not. These results suggest a possible greater involvement of IGF system in glucose regulation in patients with diabetes type 2.