Lipid Disorders
Diabetic Dyslipidaemia
It is important to monitor lipids in individuals with diabetes. Lipids testing includes Low Density Lipoproteins (LDL), High Density Lipoproteins (HDL) as well triglycerides (TG).
LDLs carry cholesterol from the liver to the blood vessel wall lining.
They are usually small and dense, are easily oxidised and engulfed by tissue macrophages and deposited onto the vessel intima lining to form cholesterol plaques. The cholesterol plaques build up quickly in diabetes and obstruct the vessel lumen. If a clot forms over it, this may result in a heart attack.
HDLs transport cholesterol from the blood vessel lumen back to the liver to be deposited and are thus seen as protective.
A deranged lipid profile is commonly seen in individuals with diabetes: total cholesterol is often elevated due to LDLs, but HDL may be low, and TGs are often elevated.
Specific drugs used to lower LDL cholesterol are called “statins”.
They work by inhibiting HMG-COA reductase, which is responsible for native cholesterol synthesis in humans. Statins have been shown in many studies to lower cardiovascular events, including heart attacks and strokes, and are indicated for treating diabetic dyslipidaemia. However, statins can have side effects, which include muscle aches, liver function abnormalities, cognitive impairment and even exacerbating glucose control. These effects are often dose dependent. Certain ethnic groups, such as Asians are more sensitive. Therefore, smaller doses of less potent “statins” may be appropriate when prescribed for Asians.
TGs are derived from fat digestion and are transported to the liver to be stored as liver fat.
TGs are metabolised by lipoprotein lipase, which is regulated by insulin. In diabetes when insulin action is lacking, TGs are not easily metabolised and therefore accumulates in the liver, leading to fatty liver disease. This can sometimes progress to cirrhosis and liver failure. Very high TGs can sometimes lead to acute pancreatitis. As TG regulation is dependent on insulin action, which is important for lowering blood glucose, having good control of one’s diabetes also means that fatty liver is treated and minimised.
Anti-lipid drugs that lower TGs are called fibrates.
A popular fibrate is fenofibrate or is known by its trade name “Lipidil”. This drug is highly effective in lowering TGs. It may also have a protective effect on reducing or halting the progression of retinopathy. It may also protect the kidneys and reduce the incidence of limb amputations. Some researchers believe that fenofibrate may protect small vessels in the kidneys and limbs. It should therefore be considered in all individuals with diabetes, regardless of TG levels.