We assessed whether Index60 could identify subpopulations with heterogeneous T1D features among autoantibody positive (Ab+) individuals with a normal 2-hour glucose. Index60 is a composite measure of fasting C-peptide, 60-minute C-peptide, and 60-minute glucose that has potential utility as a prediabetes endpoint when values are ≥1.00. Baseline 2-hour OGTTs of Ab+ TrialNet Pathway to Prevention participants in the normal 2-hour glucose (<140 mg/dl) range and low Index60 range (<1.00) were studied. The top 2-hour glucose <140 mg/dl quartile was compared with the top Index60 <1.00 quartile for characteristic T1D features (groups mutually exclusive).

Those in the top Index60 quartile (Group B) or in both top quartiles (Group C) had profiles more typical of T1D than those in the top 2-hour glucose quartile (Group A), who had higher C-peptide levels, lower Ab+ frequencies, and were older (Table).

Also, as indicated by within group odds ratios, Group A had less association of DR3-DQ2/DR4-DQ8 with the top quartile (Group A: 1.19, ns; Group B: 1.49, p<0.01; Group C: 1.63, p<0.01).

In summary, Index60 can detect heterogeneity among those with normal 2-hour glucose levels, and identify subpopulations with appreciably more characteristic T1D features. The atypia of Group A demonstrates the importance of this Index60 utility.

B.M. Nathan: None. S. Geyer: None. L.E. Bocchino: None. J.P. Palmer: None. L.M. Jacobsen: None. M.J. Redondo: None. E.K. Sims: None. J.S. Skyler: Advisory Panel; Self; ADOCIA, Applied Therapeutics, Dance Biopharm Holdings Inc., Orgenesis Ltd., Tolerion, Inc., Viacyte, Inc. Board Member; Self; Dexcom, Inc., Intarcia Therapeutics, Inc., Moerae Matrix, Inc. Consultant; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Dalcor, Dialogics, Elcelyx Therapeutics, Inc., Esperion, GeNeuro Innovation, Ideal Life, Immunomolecular Therapeutics, Intrexon, Kamada, Nestlé, Sanofi, Valeritas, Inc., Zafgen, Inc. Stock/Shareholder; Self; Dexcom, Inc., Ideal Life, Intarcia Therapeutics, Inc., Intrexon, Moerae Matrix, Inc. J.M. Sosenko: None.


National Institutes of Health; JDRF

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