n = 8s2/d2 [Eq. 1] Where n is the sample size, s is the typical error in measurement and d is the meaningful effect size. The magnitude of d was derived from 0.8 of the between subject variation, which was calculated using existing data. The postprandial incremental area under the curve (AUC) for triglyceride concentrations following a mixed-macronutrient meal in people with T1DM is typically 0.74 mmol.l-1.hour-1, with a between-subject standard deviation of 0.99 mmol.l-1.hour-1 (Levetan et al. 2003). Therefore d was calculated as 0.79 mmol.l-1.hour-1. The CV of this measure derived from repeated trials is 23% (Weiss et al. 2008), giving a typical error in the region of 0.18 mmol.l-1.hour-1. These data indicate a sample size of 18 participants provides greater than an 80% chance of detecting a statistically significant effect with a P value of < 0.05.