A six-year longitudinal study identifies a statin-independent association between low LDL-cholesterol and risk of type 2 diabetes

Background: Statin therapy has been associated with increased risk of type 2 diabetes (T2D). We investigated the relationship between Low-Density Lipoprotein Cholesterol (LDL-C) plasma concentrations and incident T2D and evaluated the modifying effect of statin therapy in a large population-based cohort. Methods: Individuals free of T2D and cardiovascular disease at baseline were followed longitudinally for the development of new-onset T2D. Cox proportional hazards models were applied to evaluate the associations of LDL-C levels and statin therapy with T2D risk. Results: From a population of 202,545 individuals, we selected 13,674 participants free of T2D and cardiovascular disease (of whom 52% were on statins), who were followed for a median of 71.6 months (IQR 34.5-149.9), during which 1,819 (13%) developed incident T2D. Cox multiple regression analysis revealed a significant inverse association between LDL-C plasma levels and incident T2D (p < 0.001). When stratifying LDL-C into quartiles [i.e. low (< 84 mg/dL), medium (≥ 84 to < 107 mg/dL), high (≥ 107 to < 131 mg/dL), and very high (≥ 131 mg/dL)], we observed that patients with LDL-C < 84 mg/dL had the highest risk of developing T2D. The interaction between statin therapy and T2D incidence was significant only in the very high LDL-C group, where statin users had a greater risk than non-users (p = 0.018); in the other three LDL-C groups, statin therapy did not significantly modify the association between LDL-C and T2D risk. Conclusions: Taken together, our findings demonstrate a strong inverse association between LDL-C and incident T2D in the general population. The increased risk of T2D at lower LDL-C levels appears to be independent of statin use, supporting the role of LDL-C as a potential biomarker of T2D susceptibility.