Getting and keeping your cholesterol in good range is one of the ABC’s for diabetes control (A1C and blood pressure are the other two). As with glucose control, lifestyle management is the foundational step of any program emphasizing heart health. But, like glucose management, diet and exercise alone aren’t always sufficient to bring your lipid values into the target range. Therefore, many people with diabetes need to take lipid lowering medications.
The four major lipid components are cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides (TG). Briefly, high LDL and TG levels are generally associated with a higher risk of coronary artery disease and higher HDL levels with lower risk. Each of the lipid-lowering medications target one or more of these lipid components.
Understanding the different categories of lipid medications and how they work can help you become a knowledgeable partner with your health care team when deciding whether a medication program is right for you.
Statins have been in use for over 30 years, and are the most effective agents we have in the war against heart disease. As a class they can lower LDL cholesterol between 20 to 60 percent. They also have limited effects on raising HDL and reducing TG levels. Statins work by blocking an enzyme called HMG-COA reductase, which has the primary role in cholesterol synthesis. This results in a deficit of cholesterol in the liver cells and causes the liver to pull cholesterol out of the blood. This happens because statins increase the number of LDL receptors in the liver, which helps clear cholesterol from the body.
Some statins are stronger than others when it comes to lowering cholesterol levels and most have evidence backing not only their LDL-lowering ability, but also their role in reducing the risk of heart attack or stroke. For example, if you need to lower your LDL only a modest amount you may be prescribed lovastatin, fluvastatin, or pravastatin, as they are less potent than atorvastatin or rosuvastatin, which are often used in people who have had a heart attack or at very high risk for it. Although rare, statins can cause muscle and liver injury.
Statins currently available in the U.S.include:
Lovastatin (Mevacor®, Altoprev™)
lRosuvastatin Calcium (Crestor®)
Statins are also found in the combination medications :
Advicor® (lovastatin + niacin), Simcor (Simvastatin + Niacin), Caduet® (atorvastatin + amlodipine), Vytorin™ (simvastatin + ezetimibe), JUVICOR ( Sitagliptin + Simvastatin)., and LIPTRUZET (Atorvastatin + Ezetimibe)
Bile acid sequestrants work in the gastrointestinal tract to bind bile acids formed and secreted from the liver (bile contains cholesterol) and removes them from the body. Bile acid sequestrants aren’t absorbed so they have few side-effects except for constipation and gas. However, the constipation can be severe so these drugs aren’t used as frequently as some others. Their major effects are on LDL levels. Common drugs in this category are Questran® and Questran Light®, Colestid® and WelChol®. They can be used along with a statin to maximize LDL lowering.
The cholesterol-absorption Inhibitor. Ezetimibe (Zetia®) is the only drug in this category. It binds to the hair like surface cells in the intestine and prevents dietary cholesterol from being absorbed. It effectively lowers LDL by 15 to 20 percent, with no significant effect on triglycerides or HDL. It is often used along with a statin to maximize LDL lowering. Zetia® has minimal side effects, but has not been proven to improve the risk of heart disease.
Fibrates are generally used in patients with high TG levels. When used in conjunction with statins they can occasionally increase the risk of muscle injury in certain patients Examples of the medications in this class of drugs include, fenofibrate (Lofibra, Tricor) and gemfibrozil (Lopid). They also have a significant effect on increasing HDL levels.
Niacin (Nicotinic acid) is used to increase HDL cholesterol. It modestly lowers triglycerides and LDL. With the ability to raise HDL up to 35 percent, it is the best drug therapy available for raising HDL. It works by multiple mechanisms including a reduction in free fatty acid mobilization from the fat tissue, which indirectly raises HDL. High levels of free fatty acids can lead to insulin resistance so reducing them improves insulin’s ability to encourage fat uptake by the liver and muscle cells.
Recent evidence has suggested that niacin, although effective in raising HDL, may have no influence on lowering the risk of heart disease, especially when LDL is sufficiently low. Side effects of niacin include flushing, itching and headaches. Doses of niacin used to raise HDL far exceed the amounts that can be consumed through food or through basic vitamin supplements. Over-the –counter medicinal dose supplements do exist, but these should be taken only under the direction of a physician. Niacin can also raise blood glucose so care should be taken when used in people who have diabetes.
Our arsenal of cholesterol lowering drugs has not grown significantly in the last thirty years, but now two other classes of drug, PCSK9 and CETP inhibitors, are undergoing clinical trials. Stay-tuned for more information on these exciting new developments.