Dr Zanariah Hussein Consultant Endocrinologist, Department of Medicine, Hospital Putrajaya
When it comes to the amount of cholesterol in your blood (or blood cholesterol, as it is sometimes known as), what we are talking about is actually a group of lipid substances, comprising the following:
- Low-density lipoprotein (LDL) cholesterol. This is known as the ‘bad cholesterol’. LDL cholesterol can become attached to the inner walls of your arteries, along with other substances to form a plaque. A plaque can cause the narrowing and even blockage of the arteries, hence high levels of LDL cholesterol can increase your risk of heart attack and stroke.
- High-density lipoprotein (HDL) cholesterol. Also known as the ‘good cholesterol’, HDL cholesterol is believed to help carry LDL cholesterol back to the liver, where the ‘bad cholesterol’ is then broken down. Therefore, it serves to reduce your risk of heart attack and stroke – the complete opposite of its ‘evil’ sibling!
- Triglycerides. These are actually a type of fat – they make up the bulk of your body fat. While the link between heart diseases and triglycerides is not as strongly established as that with LDL cholesterol, many people with high total cholesterol levels also have high triglyceride levels. Furthermore, people with diabetes and heart disease also have high triglyceride levels, so there may be a link there.
Lipoproteins? What are they?
Lipoproteins are special carrier molecules, produced by the liver to transport cholesterols and triglycerides in the blood. Fats, you see, are not water soluble, while a main component of our blood is water. A lipoprotein can bind with a cholesterol or triglyceride to create a water-soluble particle that can flow more easily in the blood stream.
Both LDL and triglycerides are naturally obtained from your diet, especially from food sources that are high in cholesterol, saturated fats and trans fat. This is why, when you are diagnosed with high levels of these substances, you are advised to make necessary adjustments to your current diet as well as to be physically active (to burn the excess fat in your body away).
When things go up
“Type 2 diabetes is a condition when the tissues of your body become less sensitive to the effects of the hormone insulin. Insulin helps to regulate the level of glucose in the blood within a healthy limit, so if you have diabetes, your blood will have higher than normal glucose levels,” says consultant endocrinologist Dr Zanariah Hussein. This insensitivity to insulin can lead to other health problems.
If you have type 2 diabetes, it has been suggested that your body’s resistance to insulin causes some abnormalities in the production of lipoproteins in the liver and/or the breaking down of triglycerides by your muscle cells. Consequently, there is an increase of total blood cholesterol and triglyceride levels. The condition in which the levels of these substances are higher than normal is called dyslipidaemia.
Effects on the cardiovascular system
When it comes to problems related to the heart and the circulatory system, Dr Zanariah says that it is often difficult to pinpoint diabetes alone as the cause, as people with type 2 diabetes also often suffer from several other health conditions that can also be risk factors.
“But we believe there is a link, because many patients with diabetes experience heart problems or have poor heart function even when their blood pressure is not too bad,” she points out.
To illustrate, she explains that high levels of LDL cholesterol may increase the risk of arterial narrowing and clogging in areas such as the heart and brain. People with diabetes, therefore, have a higher risk of stroke and heart attack, especially if they also have high blood pressure and other health conditions.
“Type 2 diabetes also tends to promote tissue injury and inflammation,” she adds, “which can only worsen any blood vessel damage that is already present.”
While more studies need to be done before we can have a clearer idea of how diabetes affects heart health, the studies done so far suggest that managing dyslipidaemia can confer some benefits to the heart health of people with diabetes.
Effects on the pancreas
While many people can easily see the association between dyslipidaemia and heart diseases, there is another important, but often overlooked, organ that can also be impacted by that condition: the pancreas.
The pancreas may not be as well known as the heart or the liver, but it is nonetheless an important organ. It is the ‘factory’ that produces insulin. Additionally, it produces several enzymes and also releases bile (a substance important for digestion, which is produced in the gallbladder) into the area of the small intestine called the duodenum. Here, these enzymes and bile perform important functions that allow for good digestion of fats, proteins and carbohydrates.
Very high triglyceride levels (over 1,000 mg/dl or 11.3 mmol/l) are considered a risk factor for acute pancreatitis.
- Acute pancreatitis happens when the pancreas becomes inflamed. If this happens to you, you will experience intense pain in the upper abdomen up to a few days if you do not seek treatment. The pain often worsens after you eat. There are also usually nausea, vomiting and fever.
- Treatment can be difficult because the pancreas is a relatively small organ (6 to 12 inches) surrounded by other organs such as the liver, small intestine and spleen. This location can make the pancreas difficult to be scanned or screened using conventional diagnostic imaging devices (X-ray, etc). Often, the only way for a doctor to see what is happening in the pancreas is via surgery. As a result, acute pancreatitis is a serious, potentially fatal condition, since it is often detected only when it has become more advanced.
- It is, fortunately, rare for people with diabetes to have such high blood triglyceride levels that they end up with acute pancreatitis. The risk remains, however, especially if they have other health conditions as well such as excess belly fat (due to being overweight or obese), high blood pressure and low HDL cholesterol levels. All of these can contribute significantly to increased levels of triglycerides in the blood. There are also genetic conditions that can contribute to increased levels of triglycerides in the blood.
- Therefore, if you have diabetes and high blood triglyceride levels, it is worth making the necessary adjustments to keep everything under control.
Keeping things under control
Dr Zanariah explains that there are three important aspects of diabetes management:
- Take all medications as prescribed, in the right dosage, and make sure you keep your medical appointments.
- Make positive changes to your diet.
- Be physically active every day.
Take your medications.
Statins, according to Dr Zanariah, are the first choice when it comes to treating dyslipidaemia. They are also useful as a pre-emptive protective measure, as patients with diabetes over 40 years old are given statins even if their lipid levels are normal, to protect them from dyslipidaemia and the health complications associated with it.
Statins reduce blood cholesterol but do not lower blood triglycerides effectively. For patients with elevated blood triglyceride levels, fibrates are usually added to statin therapy. There are several clinical studies done that demonstrate the effectiveness of fibrates in lowering triglycerides. The FIELD study, for example, showed that fenofibrate can lower triglyceride levels by up to about 27%, with greater benefits seen in patients with no history of CHD.
There may be some side effects if fibrates and statins are taken together, so take your medications only as prescribed by your doctor – don’t add anything ‘extra’ to your current medications without consulting your doctor first!
Statins vs fibrates – what’s the difference?
- Statins are most effective in lowering LDL cholesterol levels, by inhibiting the enzyme involved in production of cholesterol in the liver. When cholesterol production is decreased, the body will take in more LDL cholesterol from the blood, hence reducing its level. Examples of statins are lovastatin, rosuvastatin and simvastatin.
- Fibrates are better in lowering triglyceride levels. They can also help lower LDL cholesterol levels as well as raise HDL cholesterol levels, although the mechanisms for these actions are still unclear. Examples of fibrates are fenofibrate, clofibrate and gemfibrozil.
While taking your prescribed medications in the right dosage is important, it is just as important to keep your medical appointments. This is because blood samples taken during these medical appointments can be used to measure and monitor your total blood cholesterol and triglyceride levels, among other things. If signs of dyslipidaemia are detected early, it is then easier to bring the level down within a healthier range, before significant damage is done to your organs.
Make positive changes to your diet.
When you are diagnosed with type 2 diabetes, a dietitian will work with you to make the necessary changes to your diet. Dr Zanariah emphasizes that it is important that you put these changes into effect, as healthy, balanced meals when taken in the right portions can make a big – BIG! – difference to your efforts to stay healthy.
Also, she points out that dyslipidaemia is a condition that has little to do with carbohydrates, so carbohydrate counting – while an important step that should be carried out – will not help to improve dyslipidaemia. If you have this condition, you need to be very careful with your diet, and cut down on foods containing saturated and trans fats as well as cholesterol. Consult your dietitian for more information.
Be physically active every day.
Not only is regular physical activity good for diabetes control as a whole, studies have found that it could benefit patients with dyslipidaemia throughout their entire life.
Scott, R., et al. (2009). Effects of fenofibrate treatment on cardiovascular disease risk in 9,795 individuals with type 2 diabetes and various components of the metabolic syndrome. Diabetes Care;32(3): 493-498.
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Fernandes, R.A., et al. (2011). Prevalence of dyslipidemia in individuals physically active during childhood, adolescence and adult age. Arq Bras Cardiol.;97(4):317-23.
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