Epidemiological Aspects on Assessing and Treating Dyslipidemia in Type 1 Diabetes : Studies from the Swedish National Diabetes Register

Sammanfattning: Background: Cardiovascular disease (CVD) is a major cause of shortened longevity in individuals with type 1 diabetes. Dyslipidemia is one of the important modifiable risk factors. Aims: To investigate different aspects of dyslipidemia in type 1 diabetes. Assessing available blood lipid variables as markers of CVD risk in type 1 diabetes and the associations between lipid-lowering therapy (LLT) and CVD in primary prevention. Investigating the adherence to LLT, the association between non-adherence and CVD risk, and the factors associated with non-adherence from a demographic and socioeconomic perspective. Methods: The studies comprise individuals with type 1 diabetes registered in the Swedish National Diabetes Register (NDR). Clinical characteristics and laboratory measures were collected from the NDR together with data from other nationwide Swedish registries on health and socioeconomy. In study I, Cox regression analyses were performed to assess low-density lipoprotein (LDL)-cholesterol and total cholesterol to high-density lipoprotein (HDL)-cholesterol ratio as predictors of CVD in individuals with type 1 diabetes. In study II, the association between primary prevention with LLT and the risk of CVD was analyzed in 24,330 individuals with type 1 diabetes applying propensity scores to balance the groups. In studies III and IV, we utilized the Swedish Prescribed Drug Register to investigate adherence and non-adherence in 6192 individuals with type 1 diabetes and novel users of LLT in the context of CVD and socioeconomy. Results: Total cholesterol to HDL-cholesterol ratio was a better predictor for cardiovascular risk in primary prevention than LDL-cholesterol, with a 12% elevated risk of CVD per 1 unit increase in the ratio. Individuals with type 1 diabetes and no history of CVD had a 22-44% lower risk of CVD and cardiovascular death when on LLT compared to the untreated individuals. High adherence to LLT was associated with a 22% lower risk of non-fatal CVD compared to a lower degree of adherence. Individuals discontinuing LLT within 18 months had a 43% higher risk of non-fatal CVD. Lower adherence was associated with male gender, younger age, marital status, and country of birth. Conclusion: These observational studies emphasize the importance of regularly assessing and treating dyslipidemia in individuals with type 1 diabetes in order to achieve full cardioprotective treatment and lessen the cardiovascular burden in the type 1 diabetes population.