Treatment of the adolescent diabetic continues to be a challenge for the physician. Ninety-five diabetic patients aged from 12-18 years were treated according to several therapeutic regimens. Principally the Spanish school time-table and, in some cases, life-style or brittle diabetes, determined the adoption of one of five proposed routines. The degree of control achieved assessed by the mean levels of HbA1 (10.6-10.3%), and the frequency and severity of hypoglycaemic accidents ("mild" variety in 25-30% of patients) were similar in all groups with total pancreatic insufficiency. The switch to a four-daily injection regimen (routine 5) with a pen-injector failed to improve metabolic control but patients had more flexibility in meal size and timing. These results suggest that even in teenagers diabetes can be acceptably treated.