Serum Insulin and C-Peptide Levels Identify Insulin Resistance in Apparently Healthy Non-Hispanic Whites

Presentation Number: SUN 587
Date of Presentation: April 2nd, 2017

Fahim Abbasi*1, Dov Shiffman2, Carmen H. Tong2, James J. Devlin2, Gerald M Reaven1 and Michael J. McPhaul3
1Stanford University School of Medicine, CA, 2Quest Diagnostics, Alameda, CA, 3Medical Director, Endocrinology, San Juan Capistrano, CA

Abstract

Insulin action as quantified by measurement of insulin-mediated glucose uptake (IMGU) varies 6- to 8-fold in apparently healthy individuals, and 25 to 33 percent of such individuals are sufficiently insulin resistant to be at increased risk to develop clinical syndromes including type 2 diabetes, hypertension, and cardiovascular disease. Identifying insulin resistance (IR) before manifest disease would facilitate focused disease prevention efforts in these high risk individuals. However, since direct measurement of IR is not feasible at a clinical level, attempts have been made to identify IR using demographic and metabolic measures including body mass index (BMI), systolic blood pressure (SBP), and fasting concentrations of glucose (FPG), insulin, C-peptide, high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG)). To pursue this effort, a retrospective analysis was performed in which IMGU was assessed by determining the steady-state plasma glucose (SSPG) concentration during an insulin suppression test in 527 apparently-healthy non-Hispanic, White participants. IR was defined as being in the top quartile of SSPG values. Insulin and C-peptide concentrations were determined by a multiplexed tandem mass spectrometry assay to measure intact insulin and C-peptide (Taylor ST, 2016). All other biomarkers were assessed by standard methods. For 278 of the participants all anthropometric measures (age, sex, SBP, and BMI) and biomarkers (FPG, insulin, C-peptide, HDL-C, TG, creatinine, and alanine aminotransferase (ALT) were available. Among these 278 participants, FPG, insulin, C-peptide, HDL-C, BMI, ALT, SBP, and creatinine were significantly associated (P= 0.04 to <0.001) with SSPG values when adjusted for age and sex. Using forward and backward model selection, we found that an IR model that included only insulin, C‑peptide, and BMI had an AUC of 0.90. When model selection was restricted to biomarkers, a model that included only insulin and C-peptide had an AUC of 0.89. In conclusion, fasting insulin and C-peptide concentrations were both correlated with SSPG concentration, and the combination of these two measurements provided accurate information as to the presence of IR in a population of apparently-healthy non-Hispanic, White individuals.

 

Disclosure: DS: Employee, Quest Diagnostics. CHT: Employee, Quest Diagnostics. JJD: Employee, Quest Diagnostics. GMR: Consultant, Quest Diagnostics. MJM: Employee, Quest Diagnostics, Employee, Quest Diagnostics. Nothing to Disclose: FA