Endocrine Abstracts

Background: Insulin dose requirements are higher during puberty and in overweight/obese individuals with type 1 diabetes mellitus (T1DM) due to insulin resistance. Through meta-analysis metformin has been shown to be beneficial as adjunctive therapy in T1DM adults independent of BMI. The large volumes of insulin required to administer higher insulin doses in insulin-resistant individuals have adverse effects on insulin absorption. Insulin degludec (Tresiba) U200 preparation allows lesser volume administration for the same dose. We describe a 16-year-old girl with T1DM whose basal insulin requirement decreased markedly when switching to insulin degludec (Tresiba) U200 with the addition of metformin.

Case: The patient was diagnosed with T1DM at the age of 5 years. GAD and islet cell antibodies were positive. HbA1c at diagnosis was 89 mmol/mol. Initial management was with multiple daily insulin (MDI) injections. At age 9 years she switched to continuous subcutaneous insulin infusion (CSII). At age 15 years she chose to change back to MDI due to recurrent skin abscess formation. The patient increased her basal insulin detemir (Levemir) doses from 0.6 U/Kg per day up to 1.9 U/kg per day over 8 months following the switch. During this period HbA1c increased slightly from 58 to 64 mmol/mol and BMI increased from 23.4 to 24.8 kg/m². There were no episodes of ketoacidosis. She was trialed on insulin degludec (Tresiba) U200 at 30% reduced dose (1.3 U/kg per day) with addition of modified release metformin. Over the first 4 weeks following switch, due to recurrent hypoglycaemia, her basal insulin requirement reduced further to 0.7 U/kg per day (60% reduction in basal insulin dose).

Conclusions: Insulin degludec U200 preparation can be useful in T1DM patients requiring high basal insulin doses. Metformin is a useful adjuvant therapy in post pubertal T1DM patients with insulin resistance. Close monitoring is required over first weeks of therapy with insulin degludec (Tresiba) and metformin.