Background/Purpose: Amylin is a 37-amino acid peptide that is stored in pancreatic beta cells and is co-secreted with insulin. Amylin and insulin levels rise and fall in a synchronous manner. It is know that it is deficient in type 1 diabetes and relatively deficient in insulin-requiring type 2 diabetes. Similarly, chronic inflammation has been found to deteriorate insulin resistance (IR) and impair pancreatic beta cell function in rheumatoid arthritis (RA) patients. The aim of this study was to explore the role of amylin in the IR of RA patients.

Methods: Cross-sectional study that encompassed 361 non-diabetes individuals; 151 patients with RA and 210 age- and sex-matched controls. IR by homeostatic model assessment (HOMA2), insulin and C-peptide serum levels and amylin serum levels were assessed in patients and controls. A multivariable regression analysis, adjusted for IR related factors, was performed to evaluate the differences between patients and controls in amylin and how amylin is related to IR, disease activity and disease characteristics in RA patients. Fisher r-to-z transformation was used to compare Pearson’s r2 between patients and controls.

Results: HOMA2-IR indexes were higher in RA patients compared to controls. Similarly, insulin and C-peptide were superior in RA controls after multivariable analysis that included IR related factors and glucocorticoid intake. However, although amylin was found to be up regulated in the univariate analysis (1.36±8.81 vs. 1.79±1.51 ng/ml, p=0.011), this difference was lost after multivariate analysis (p=0.46). In RA patients, amylin showed a trend to be related with erythrocyte sedimentation rate (beta coef. 0.01 [95%CI -0.00-0.01], 0.07). Similarly, the presence of rheumatoid factor (beta coef. 0.90 [95%CI -0.23-1.56], p=0.009) and disease activity through SDAI was positively associated with amylin (0.01 [95%CI 0.00-0.03], p=0.034). This relation was not found with DAS28 or CDAI. The use of prednisone, methotrexate or anti-TNF therapies was not associated with amylin neither insulin nor C-peptide. Differences in the relation of insulin, C-peptide, amylin and HOMA2 indexes between each other and between populations were assessed. In this sense, relation between insulin and C-peptide (r2 0.817 vs. 0.947, p=<0.001), between C-peptide and HOMA2-IR (r2 0.831 vs. 0.948, p<0.001), between insulin and HOMA2-%B-C peptide (r2 0.689 vs. 0.872, p<0.001) and between C-peptide and HOMA2-%B-C peptide (r2 0.827 vs. 0.922, p<0.001) were higher in controls compared to RA patients. Amylin had no relation with C peptide, insulin or HOMA2-IR and these relations were not different between patients and controls.

Conclusion: The mechanism that produces IR in RA patients may not be mediated by amylin.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/amylin-in-the-insulin-resistance-of-patients-with-rheumatoid-arthritis/