Nathan BM, Redondo MJ, Ismail H, et al. - Index60 (a composite measure of fasting C-peptide, 60-min C-peptide, and 60-min glucose) has the ability to detect people with characteristics of type 1 diabetes at appreciable risk for progression who would otherwise be missed by 2-h glucose staging criteria.

• This study included 3,058 Type 1 Diabetes TrialNet Pathway to Prevention participants with 2-h glucose <140 mg/dL and Index60 <1.00 values from baseline oral glucose tolerance tests.

• Four mutually exclusive groups were defined: top 2-h glucose quartile only (HI-2HGLU), top Index60 quartile only (HI-IND60), both top quartiles (HI-BOTH), and neither top quartile (LO-BOTH), among which features linked with type 1 diabetes were compared.

• Younger age, greater frequency of more than two autoantibody-positive (Ab ⁺ ), and lower C-peptide levels were detected in HI-IND60 and HI-BOTH, vs either HI-2HGLU or LO-BOTH.

• For HI-IND60 and HI-BOTH, a greater cumulative incidence for stage 3 was reported than for either HI-2HGLU or LO-BOTH.

• Younger age and higher frequency of two or more Ab ⁺ and DR3-DQ2/DR4-DQ8 prevalence and lower area under the curve (AUC) C-peptide levels were seen in those with Index60 values above the median vs those below.

• Higher AUC C-peptide levels were detected in those above the 2-h glucose median, but otherwise did not differ from those below.