Seventy-one adolescents ( mean age : 15 years , mean duration of diabetes : 5.7 years , mean HbA1c : 77 mmol/mol ( 9.1 % ) , upon entering the study ) from two pediatric departments were randomized into a GSD-Y group ( n = 37 , GSD-Y was provided during individual outpatient sessions ) versus a treatment-as-usual group ( n = 34 ) .