Analyzing doubly repeated measures: Area under the curve and mixed model approaches

An oral glucose tolerance test (OGTT) measures glucose at several time points following ingestion of a glucose solution.  The aim is to determine the pattern of change in glucose levels as an indication of how efficiently the individual is disposing the glucose from the blood.  Traditionally, assessing the shape of the glucose curves before and after intervention is primarily done via area under the curve (AUC).  If an intervention is given and the process is repeated under this new condition, the data may be analyzed using a doubly repeated measures model.  Using data simulated under the null hypothesis of no intervention effect, p-values are compared between the AUC analysis and the doubly repeated measures (mixed) model approach.  The goal is to determine if the hypothesis tests performed using the two methodologies result in different type I error rates.  Special focus is given to data that produce p-values from the two approaches that are highly different.