How is my high cholesterol treated if I also have diabetes?

According to the 2018 American Heart Association (AHA)/ American College of Cardiology (ACC) Guidelines for the Management of Blood Cholesterol, moderate intensity statin therapy is strongly recommended for patients with diabetes mellitus who are 40 to 75 years of age along with healthy lifestyle interventions, regardless of their estimated 10-year risk of atherosclerotic cardiovascular disease (ASCVD).¹ Generally, diabetics in this age range are at intermediate or high-risk of ASCVD² and statins have been shown to reduce this risk.^3,4 A meta-analysis of four double-blind primary prevention trials showed a 25% reduction of ASCVD risk after moderate-intensity statin use in people with type 1 and type 2 diabetes.⁴ High-intensity statins are strongly recommended if, in addition to the presence of diabetes, the low-density lipoprotein cholesterol (LDL-C) level is ≥190 mg/dL or if cardiovascular disease has already been diagnosed.¹ High-intensity statins have been shown to reduce LDL-C levels by 50% or more in some people.

Over time, diabetics may accrue additional risk factors and the 2018 ACA/AHA guidelines consider it reasonable to estimate a 10-year risk of ASCVD events using a Pooled Cohort equation to determine the need to increase the intensity of statin therapy or to add other medications.^1,2 The Pooled Cohort equation is a risk calculator that was developed and validated among black and Caucasian men and women without clinical ASCVD to estimate future risk of cardiovascular events.^5,6 While there have been no randomized controlled trials of high-intensity statin therapy in diabetics specifically, there is good evidence that high intensity statin therapy can lower risk in individuals with multiple ASCVD risk factors.⁷

If the estimated 10-year risk of an ASCVD event is high (over 20%) it may also be reasonable to add ezetimibe to the maximally tolerated statin regimen, although evidence of the effect on the ASCVD outcomes is limited.^8,9 Data from the Cholesterol Treatment Trialists Collaboration⁷ has demonstrated that the higher the 10-year risk for an ASCVD event, the greater the benefit from lowering LDL-C with statins. Adding ezetimibe 10 mg to a moderate-intensity statin regimen had the same LDL-C lowering effect as high-intensity statin therapy in a study of 9,077 patients who had been hospitalized with acute coronary syndrome.⁸  

The 2018 AHA/ACC cholesterol guidelines also consider it reasonable, once started, to continue on statin therapy or to consider starting statin therapy at age 75 and older, but no controlled statin trials exist for this age group.^1,10 It is also reasonable to consider stopping statin therapy in frail individuals over 75 with multiple comorbidities or if reduced life expectancy limits the potential benefits of statins. Observational data does support continuing statin therapy among individuals in this age group if they have diabetes.¹¹

Although there is no information on the benefit of statin therapy in diabetics under 40 years of age, there is some evidence that the estimated 10-year risk of ASCVD may reach intermediate levels in individuals with long-standing diabetes.¹² According to the 2018 ACA/AHA guidelines, it is reasonable to consider statin therapy depending on duration of diabetes, kidney function, and other clinical factors that enhance the risk of ASCVD.¹ Based on estimated cardiovascular risk, it is reasonable to consider the use of statins if an individual has had type 2 diabetes for 10 or more years,¹² type 1 diabetes for 20 or more years,¹³ albuminuria (≥30 mcg of albumin/mg of creatinine),¹⁴ estimated glomerular filtration rate <60 mL/min/1.73m²,¹⁴  retinopathy,¹⁵ neuropathy,¹⁶ or ankle-brachial index <0.9.¹⁷

^References

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2. Wong ND, Glovaci D, Wong K, et al. Global cardiovascular disease risk assessment in United States adults with diabetes. Diabetes Vasc Dis Res 2012; 9 (2): 146-152.
3. Colhoun HM, Betteridge DJ, Durrington PN, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 2004; 364 (9435): 685-696.
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