Comprehensive validation of fasting-based and oral glucose tolerance test-based indices of insulin secretion against gold standard measures.

INTRODUCTION: With pre-diabetes and diabetes increasingly recognized as heterogeneous conditions, assessment of beta-cell function is gaining clinical importance to identify disease subphenotypes. Our study aims to comprehensively validate all types of surrogate indices based on oral glucose tolerance test (OGTT) and fasting measurements in comparison with gold standard methods. RESEARCH DESIGN AND METHODS: The hyperglycemic clamp extended with glucagon-like peptide 1 (GLP-1) infusion and intravenous glucose tolerance test (IVGTT), as well as OGTT, was performed in two well-phenotyped cohorts. The gold standard-derived indices were compared with surrogate insulin secretion markers, derived from fasting state and OGTT, using both Pearson's and Spearman's correlation coefficients. The insulin-based and C-peptide-based indices were analyzed separately in different groups of glucose tolerance and the entire cohorts. RESULTS: The highest correlation coefficients were found for area under curve (AUC) (I0-30)/AUC (G0-30), I30/G30, first-phase Stumvoll and Kadowaki model. These indices have high correlation coefficients with measures obtained from both insulin and C-peptide levels from IVGTT and hyperglycemic clamp. AUC (I0-120)/AUC (G0-120), BIGTT-AIR0-60-120, I30/G30, first-phase Stumvoll and AUC (I0-30)/AUC (G0-30) demonstrated the strongest association with incretin-stimulated insulin response. CONCLUSIONS: We have identified glucose-stimulated and GLP-1-stimulated insulin secretion indices, derived from OGTT and fasting state, that have the strongest correlation with gold standard measures and could be potentially used in future researches and clinical practice.

Interleukin 23 expression in pyoderma gangrenosum and targeted therapy with ustekinumab.

BACKGROUND: Interleukin (IL)-23 is involved in the pathogenesis of the chronic inflammatory Crohn disease. Pyoderma gangrenosum (PG) is often associated with and can even be the first manifestation of this disease and has abundant neutrophilic infiltration. Because IL-23 plays a critical role in driving inflammation associated with IL-17 production and especially neutrophil recruitment, we suspect that PG might be driven by a pathogenetic mechanism similar to that of inflammatory bowel diseases or psoriasis. OBSERVATIONS: Tissue sample analysis showed highly elevated expression of IL-23 on both transcriptional and protein level in a recalcitrant PG lesion. On the basis on these data, a treatment targeting the p40 subunit of the heterodimeric IL-23 with the monoclonal antibody ustekinumab was started. Therapy with ustekinumab resulted in a significant decrease of IL-23 expression in PG and healing after 14 weeks of treatment. No relapse occurred in a 6-month follow-up period. CONCLUSIONS: Our data provide evidence of an IL-23-dominated inflammatory infiltrate in PG. This might specify a new concept for PG pathophysiology and suggests a possibility for using ustekinumab as a therapeutic agent in this disease.