Mixed-meal tolerance tests vary for C-peptide response in T1DM

(HealthDay)—Two- and four-hour mixed-meal tolerance tests (MMTTs) vary for C-peptide responses in type 1 diabetes, according to research published online April 13 in Diabetes Care.

Karen D. Boyle, from Rho Federal Systems Division in Chapel Hill, and colleagues examined the effect of abbreviating the MMTT test using data from 186 patients participating in three clinical trials conducted by the Immune Tolerance Network. Data were included for up to three four-hour MMTTs for each patient, conducted yearly, for a total of 506 paired two- and four-hour observations. The four-hour assessment was selected as the reference.

The researchers observed variation in the percent of the total four-hour C-peptide area under the curve (AUC) captured in the first two hours, from 28 to 72 percent. The correlation between the two- and four-hour mean AUCs (mAUCs) was 0.98. The variability of the two-hour test was generally greater than the four-hour test; the variability was similar after adjustment for baseline. When the time to peak was <120 minutes, the two-hour mAUC generally overestimated the four-hour assessment, and vice versa for times >120 minutes.

"Because the impact of the abbreviated test is differential over time and by age and treatment groups, estimates and significance tests for two- and four-hour assessments may be inconsistent," the authors write.

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