Statistical analysis
Summary statistics are reported as mean (for continuous variables) or frequency and percentage (for categorical variables), with 95% confidence intervals, unless otherwise stated. Characteristics (HbA1c, weight, number of side effects, tolerability) of the participants on the three drugs were compared using mixed effects models, to allow for repeated measures, with drug coded as a dummy variable and participant as the random effect. Chi-squared tests were used to compare differences in proportions against the null hypothesis of equal preference (i.e. 1/3). Mixed effects models were used to determine the difference in outcome (HbA1c, weight, number of side effects) between preferred and non-preferred drugs (binary variable, fixed effect), adjusting for study period (dummy variable) with participant as the random effect to allow for repeated measurements. All analysis was carried out using a validated version of Stata v16.1.