To Örebro University

AIMS/HYPOTHESIS: To study the progression of HbA1c after diagnosis of type 1 diabetes in children and adolescents during 2010-2019 with emphasis on HbA1c nadir 3-6 months after onset.

METHODS: Partial funding was secured for this study. The Swedish paediatric diabetes quality register SWEDIABKIDS has >95 % coverage of type 1 diabetes up to 18 years. A mixed model for repeated measurements was used to estimate differences in HbA1c between onset year periods.

RESULTS: We followed 6,891 patients over two years from onset (48,292 HbA1c values). We found a gradual decrease in mean HbA1c 24 months after onset from 56.0 mmol/mol (7.28 %) in 2010/11 to 50.5 mmol/mol (6.77 %) in 2018/19, which is at the level of several recent intervention studies. The initial drop in HbA1c from onset until 3 and 6 months has become more pronounced in recent years. There was a significant positive correlation between HbA1c at 3 and 6 months with 12, 18 and 24 months. Percentage of severe hypoglycaemic coma was higher (5.1 % vs 3.4 %; p = 0.023) in 2010/2011 than 2018/2019, but the absolute risk of ketoacidosis was essentially unchanged, (1.5 % to 0.8 %, p = 0.110)

Conclusions/interpretation: There was a continuous decrease in HbA1c over the study period 2010-2019, which coincides in time with an increased use of diabetes technology and lowering the HbA1c target to 48 mmol/mol (6.5 %). The decrease in 2-year HbA1c was preceded by a lower HbA1c nadir, which may set the trajectories for coming HbA1c and be a modifiable factor for a long-term improvement in metabolic control.