Endocrine Abstracts

Introduction: SFRP-4 is a recently described inflammatory cytokine influencing insulin secretion from human β cells as an extracellular modulator of Wingless (Wnt) pathway. The aim of this study is to compare serum SFRP-4 levels in patients with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and type 2 diabetes (T2DM), and to investigate its relation with other parameters.

Methods: The study included 152 patients who applied to the endocrinology outpatient clinic of our hospital. Eighty-two patients who had history of T2DM constituted the T2DM group. Patients who underwent OGTT within the last three months were categorized in either IGT (n=34) or NGT (n=36) groups according to their test results. All patients provided blood samples between 08 am and 09 am following overnight fasting. Fasting insulin, fasting glucose, HbA1c and SFRP-4 levels were measured.

Results: T2DM group had significantly higher serum SFRP-4 levels compared to BGT and NGT groups (0.282 ng/ml vs 0.183 ng/ml, P=0.001; and 0.282 ng/ml vs 0.170 ng/ml, P=0.004, respectively). In comparison of BGT and NGT groups, although serum SFRP-4 levels were higher in BGT group, the difference was not statistically significant (0.183 ng/ml vs 0.170 ng/ml, P=0.630). SFRP-4 level showed significant positive correlation with fasting glucose (r=0.274, P=0.001) and HbA1c (r=0.291, P=0.002) levels.

Conclusion: Progressive β cell dysfunction is observed during the normal course of T2DM, and inflammatory cytokines are held responsible. Recent studies have demonstrated the association between increased SFRP-4 expression on β cells and reduced insulin release. Additionally, studies have found an association between serum SFRP-4 levels and high fasting glucose level and impaired insulin sensitivity in non-diabetic individuals. We found increased serum levels of SFRP-4 in patients with T2DM in our study, and SFRP-4 level was positively correlated with fasting glucose and HbA1c levels in the whole study group. We think our results support the idea that increased plasma SFRP-4 levels may be a good indicator of β cell dysfunction and insulin resistance.