Twenty-seven youth with Ab? and 15 youth with Ab+ clinically diagnosed T2DM underwent a mixed-meal test (Boost; 55 % carbohydrate, 25 % protein, and 20 % fat). Fasting and mixed-meal-derived insulin and C-peptide indices of IS, secretion (30-minute insulinogenic [¦¤I30/¦¤G30] and C-peptide [¦¤C30/¦¤G30]), and oDI were calculated.
Indices of insulin secretion were ¡«40 % -50 % lower in patients with Ab+ T2DM compared with those with Ab? T2DM. After controlling for body mass index, ¦¤I30/¦¤G30, ¦¤C30/¦¤G30, C-peptide area under the curve (AUC)/glucose AUC, and insulin AUC/glucose AUC were significantly (P?<?.05) lower in the Ab+ group compared with the Ab? group. Sensitivity indices were significantly higher in the Ab+ group. The oDI, 1/fasting insulin?¡Á?¦¤I30/¦¤G30 (0.04?¡À?0.02 vs 0.12?¡À?0.02 mg/dL?1; P?=?.005), and 1/fasting C-peptide?¡Á?¦¤C30/¦¤G30 (0.02?¡À?0.009 vs 0.05?¡À?0.006 mg/dL?1; P?=?.018) were lower in the Ab+ group. Receiver operating characteristic curve analyses revealed that fasting C-peptide <3.2 ng/mL had 87 % sensitivity and 74 % specificity and ¦¤C30/¦¤G30 <0.075 ng/mL per mg/dL had 93 % sensitivity and 80 % specificity for identifying youth with Ab+ T2DM.
During a liquid mixed-meal test, indices of ¦Â-cell function were lower and IS was higher in patients with Ab+ T2DM versus those with Ab? T2DM, with high sensitivity and specificity for fasting and stimulated C-peptide as markers of Ab+ status. Indices of insulin secretion during this standardized mixed-meal test could be used to assess ¦Â-cell function in therapeutic trials of ¦Â-cell restoration in youth with T2DM.