AIMS/HYPOTHESIS: Metabolic abnormalities such as central obesity, insulin resistance, dyslipidaemia and hypertension, often referred to as 'the metabolic syndrome' (or 'combined metabolic abnormalities'), are increasingly being identified in people living with type 1 diabetes, accelerating the risk for CVD. As a result, in recent years, treatment in people living with type 1 diabetes has shifted to improving overall metabolic health rather than glucose control alone. In Belgium, diabetes care for people living with type 1 diabetes is centrally organised. The Initiative for Quality Improvement and Epidemiology in Diabetes, imposed by the Belgian health insurance system, has systematically collected data from patients on intensive insulin therapy treated in all 101 diabetes clinics in Belgium since 2001. The aim of this real-world study is to describe the evolution of treatment and metabolic health, including the prevalence of obesity and combined metabolic abnormalities, in people living with type 1 diabetes over the past 20 years, and to compare the treatment and prevalence of complications between those with and without combined metabolic abnormalities.
METHODS: We analysed data on adults (≥16 years old) living with type 1 diabetes, who were diagnosed at age ≤45 years and who had a diabetes duration ≥1 year, collected between 2001 and 2022. The evolution of HbA1c, BMI, LDL-cholesterol, systolic BP, lipid-lowering therapy and antihypertensive therapy over time was analysed. The prevalence of individual and multiple metabolic abnormalities according to various definitions of the metabolic syndrome/combined metabolic abnormalities was analysed, and the association between combined metabolic abnormalities and metabolic health indicators, complications and treatment was investigated in the 2022 data.
RESULTS: The final dataset consisted of 26,791 registrations of adults living with type 1 diabetes collected between 2001 and 2022. Although glycaemic and lipid control generally improved over time, the prevalence of obesity strongly increased (12.1% in 2001 vs 21.7% in 2022, p<0.0001), as did the presence of combined metabolic abnormalities (WHO criteria: 26.9% in 2001 vs 42.9% in 2022 in women, p<0.0001; 30.4% in 2001 vs 52.1% in 2022 in men, p<0.0001; WHO criteria without albuminuria: 22.3% in 2001 vs 40.6% in 2022 in women, p<0.0001; 25.1% in 2001 vs 49.2% in 2022 in men, p<0.0001; NCEP-ATPIII criteria: 39.9% in 2005 vs 57.2% in 2022 in women, p<0.0001; 40.8% in 2005 vs 60.9% in 2022 in men, p<0.0001; IDF criteria: 43.9% in 2005 vs 59.3% in 2022 in women, p<0.001; 33.7% in 2005 vs 50.0% in 2022 in men, p<0.0001). People with combined metabolic abnormalities had higher glucose levels compared to those without combined metabolic abnormalities (HbA1c >58 mmol in men: 48.9% vs 36.9%; HbA1c >58 mmol in women: 53.3% vs 41.1%, p<0.0001). People with combined metabolic abnormalities were more often treated with adjunct therapies such as metformin, sodium-glucose transport protein 2 inhibitors and glucagon-like peptide-1 receptor agonists. In both men and women, the presence of combined metabolic abnormalities was strongly related to the presence of eye complications, peripheral neuropathy, chronic kidney disease and CVD, corrected for age, diabetes duration and HbA1c.
CONCLUSIONS/INTERPRETATION: Overweight, obesity and combined metabolic abnormalities are increasingly being identified in people living with type 1 diabetes, further accelerating the risk of microvascular and macrovascular complications. Early identification of the presence of combined metabolic abnormalities should enable therapeutic interventions to be modified towards multifactorial approaches, with attention to education on avoidance of overweight (e.g. dietary counselling) in addition to strict glycaemic control and intensification of use of antihypertensive agents and statins. Use of adjunct therapies in this population as a tool should be explored more thoroughly to reduce risk of complications.