People with Type 2 Diabetes on Premixed Insulin Therapy: How is the Daily Insulin Dose Partitioned and are there Effects on the Metabolic Control?

Aim: To investigate the correctness of the recommendation for dose distribution in premixed insulin therapy, with two thirds of daily insulin dose before breakfast and one third of daily insulin dose before dinner. Methods: The individual insulin dose distribution and metabolic control of people with Type 2 diabetes treated with premixed insulin therapy were studied in a cross sectional study involving 199 patients in a university outpatient department and 2 general practices in 2010. Results: All 199 patients were treated with premixed human insulin. The mean pre-breakfast dose was 57% (min. 32%, max. 83%) and the mean pre-dinner dose 43% (17-67%) of the total daily insulin. A pre-breakfast dose of exactly two thirds of total daily insulin was used by 6.5% (n=13), about two thirds, i.e., 60-70%, was injected by 27.6% of the patients. The diurnal insulin distribution<60%, 60% up to 70% and >70% pre-breakfast insulin did not make any difference in HbA1c, which was 7.3% (56 mmol/mol) each. Conclusion: The quite common recommendation in German and Austrian medical textbooks, that premixed insulin therapy should consists of a dose distribution with two thirds before breakfast and one third before dinner, is not observed in daily practice. Diurnal insulin dose distribution and HbA1c are not associated in this cohort. Novelty statement: The circadian insulin dose distribution of 2/3 before breakfast and 1/3 before dinner could not be confirmed for patients with diabetes type 2 and conventional insulin therapy. No correlation between metabolic control and insulin circadian insulin dose distribution was detected.