Eight participants with complication-free type @ diabetes , whose mean SEM age was @ ( @ ) years , mean SEM HbA ( @c ) concentration was @ @ mmol/mol ( @ @ % ) and mean SEM type @ diabetes duration was @ @ years , attended the research facility after an overnight fast on four separate occasions , having administered their basal insulin the night before ( glargine @ U , n = @ ) , but omitted morning rapid-acting insulin .