Eight participants with complication-free type 1 diabetes , whose mean SEM age was 38 ( 6 ) years , mean SEM HbA ( 1c ) concentration was 71 11 mmol/mol ( 8.7 1.0 % ) and mean SEM type 1 diabetes duration was 15 13 years , attended the research facility after an overnight fast on four separate occasions , having administered their basal insulin the night before ( glargine 27.53.1 U , n = 8 ) , but omitted morning rapid-acting insulin .