Adding to the spectrum of insulin sensitive populations for mixed meal tolerance test glucose reliability assessment

Abstract

As a measure of insulin sensitivity, the mixed meal tolerance test (MMTT) is a simple technique that can provide robust results. The assay consists of examining plasma glucose, insulin and C-peptide prior to and following the consumption of a test meal. While this procedure has been used in clinical research for several years, there is no set standard protocol, and only until recently has the reliability of this assay been thoroughly evaluated in prediabetes and type 2 diabetes subjects. Interestingly, the results from this recent study demonstrated stronger MMTT reliability for the prediabetes and diabetes cohorts compared to obese controls. This finding suggests that the obese control group may have more inherent variability in glucose response during a meal challenge likely due to compensatory influences typically observed in non-diabetic insulin-resistant subjects. Furthermore, this study raises the question whether the MMTT assay is reliable in a non-obese cohort. Therefore, to promote the standardization of this technique and contribute to the band of insulin sensitive populations, we employed the same methodology and test meal as the reference study to evaluate the MMTT reliability in healthy and overweight men. Indeed, the interclass coefficient revealed high glucose response repeatability during the MMTT in insulin-sensitive men. Overall, the MMTT is a reliable test across a range of insulin sensitivity including healthy men. However, we propose further investigation may be required to fully define the utility of this methodology in obese non-diabetic insulin-resistant populations.

Keywords: MMTT; Postprandial glucose; Reliability.

Figures

Fig. 1

Average glucose response to a MMTT. a-d Average plasma glucose during the MMTT over five test days from four subjects. Results presented as mean ± SD, n = 5. e Group average glucose curve presented as mean ± SD, n = 4. Glucose curves were analyzed by two-way ANOVA followed by Dunnett’s post-hoc test where *p < 0.05, **p < 0.01, ***p < 0.001 vs. time 0. No one day was significantly different from another. f Box and whisker plot of average area-under-the-curve (AUC) for subjects 1 to 4 and group average. Group AUC demonstrated low within-subject (2–4%) and between-subject (6%) variation as determined by percent coefficient of variation