Accurate measurement of islet function after clinical islet transplantation (CIT) is challenging. Maximum insulin secretion can be estimated from the acute insulin response to glucose (AIRg) during frequently sampled intravenous glucose tolerance tests (FSIGT). BETA-2, a composite measure derived from a single blood test is practical for routine use. To test the validity of BETA-2, we examined its relationship with AIRg in subjects participating in CIT Consortium trials. 128 C-peptide negative subjects (48.2 ± 10.9 yrs, 38.7% male) underwent 355 FSIGTs prior to and every 6 months after CIT. They received 1-3 islet infusions of >4000 IE/kg. AIRg was derived using the minimal model. BETA-2 was calculated within 90 days of FSIGT (>75% were within 1 day). BETA-2 is plotted against log (AIRg+1) with a loess smoothing curve. BETA-2 is linearly related to log(AIRg) particularly when AIRg > ∼ 6.5 (ie log(AIRg +1) > 2). A linear regression, after raising AIRgs below 6.5 to 6.5, shows an intercept close to 0, a slope of 8.71, and an R2 of 0.69. Limiting the linear regression to test pairs done on successive days had no significant or meaningful effect on this relation. BETA-2 is highly correlated with AIRg, which is related to maximum insulin release and can be used as a validated measure to estimate beta cell mass in CIT.
P.A. Senior: None. M.R. Rickels: Consultant; Self; Semma Therapeutics, Inc. Research Support; Self; Xeris Pharmaceuticals, Inc. T. Eggerman: None. L. Bayman: None. J. Qidwai: None. R. Alejandro: None. J.F. Markmann: None. L.G. Hunsicker: Advisory Panel; Self; Allergan plc., Bristol-Myers Squibb.
