Impact of early and tight HbA1c control on the risk of long‐term complications and cardiovascular death in patients with type 2 diabetes from the Swedish National Diabetes Register

AIMS: To assess the relationship between haemoglobin A1c (HbA1c) levels and incidence of long-term complications in patients with type 2 diabetes (T2D). MATERIALS AND METHODS: This long-term, retrospective study acquired patient data from the Swedish National Diabetes Registry and linked national registers between 1 January 1998 and 31 December 2019. The incidence rates (IR) of microvascular/macrovascular outcomes and cardiovascular death were reported for the overall study population. The hazard ratios (HR) for these outcomes were compared across HbA1c ranges assessed over time and between the early HbA1c control groups: early tight control (HbA1c ≤6.5%), no early tight control (HbA1c >6.5%), and early adverse control (HbA1c >7%), from 18 months after diagnosis. RESULTS: 57.2% of the overall population were male and a median age of 60 years. The IR per 100-patient-years of any microvascular complication remained relatively stable (2005: 8.75; 2014: 10.95; 2019: 8.71), while cardiovascular death increased from 2005 (IR: 0.12) to 2018 (IR: 0.46). Incidences of any macrovascular complication increased with HbA1c ranges (8.0% to