The Issue of the Blood Vessels
Cardiovascular diseases include conditions such as heart attack, stroke, and diseases of the leg arteries, known as peripheral arterial occlusive disease. The underlying cause of these conditions is changes in the arteries, referred to as atherosclerosis.
Arteries are the blood vessels that carry blood away from the heart to the organs and limbs. They supply the muscles, the heart, and other organs with blood that has been enriched with oxygen in the lungs. If a sudden blockage occurs in the vessels supplying the heart, parts of the heart muscle are no longer adequately supplied with blood, resulting in a heart attack. The heart muscle tissue dies due to insufficient oxygen supply. If a vessel supplying oxygen-rich blood to the brain becomes blocked, a stroke occurs—meaning that part of the brain dies because of a lack of oxygen.
Deposits in the Arteries
Arteries consist of three layers:
The inner layer (intima) is lined with cells called endothelial cells. These cells form the interface with the blood and have multiple functions essential for maintaining blood flow. Atherosclerosis begins at this layer when endothelial cells initially lose some of their normal functions. This is known as endothelial dysfunction.
As atherosclerosis progresses, deposits form within the blood vessels. These deposits consist of components of the blood and blood lipids and lead to calcification of the vessels. This process is referred to as arterial calcification or atherosclerosis. Some specialists believe that atherosclerosis begins as early as fetal development and progresses throughout life. Genetic factors play a major role.
It is well established that, with increasing age, certain factors contribute significantly to the development of atherosclerosis. These include disorders of lipid metabolism, diabetes mellitus, high blood pressure, and smoking. Lipid metabolism disorders, high blood pressure, and impaired glucose tolerance form the so-called “deadly triad” of metabolic syndrome, which is associated with a high risk of cardiovascular disease.
What Does This Have to Do with Diabetes?
Mortality from cardiovascular disease is approximately twice as high in people with diabetes compared with non-diabetics, with heart attack being the most common cause of death. Despite effective management of risk factors, the risk of death remains elevated in people with diabetes.
This means that lowering cholesterol, high blood pressure, excess body weight, and elevated blood glucose reduces the risk of heart attacks, strokes, and death in people with diabetes as well. However, these effects are weaker in diabetics, which is why treatment goals should be pursued more strictly and lower target values should be aimed for.
Cholesterol Targets Are Different in Diabetes
Measuring cholesterol levels is an important risk marker for heart attacks and other vascular diseases. Measurement of “bad” LDL cholesterol has long been established for risk assessment and for guiding cholesterol-lowering therapy. Other lipid values, such as “good” HDL cholesterol and triglycerides, are of secondary importance and are not primary targets of therapeutic intervention. Blood pressure and body weight must also be lowered more aggressively or treated earlier.
LDL Cholesterol — the “Bad Guy”
Target LDL cholesterol levels are stricter in people with diabetes:
These target values are so low that they can usually only be achieved with medication. Statins such as pravastatin, atorvastatin, or simvastatin are the first-line treatment; they inhibit cholesterol production in the liver. They can be supplemented with ezetimibe, which inhibits cholesterol absorption in the intestine. High-dose statins reduce LDL cholesterol by approximately 30% from baseline, while ezetimibe reduces it by about 15%.
More recently, antibodies targeting an inhibitor of LDL breakdown—PCSK9 antibodies such as alirocumab and evolocumab—have become available. These reduce LDL cholesterol by approximately 50–60% and are currently the most potent LDL-lowering agents. All three types of medication can be combined, making it possible to achieve strict LDL cholesterol targets in nearly all patients.
Mediterranean Diet Always Helps
A low-cholesterol diet, known as the Mediterranean diet (“Mediterranean cuisine”), which includes olive oil, garlic, plenty of fresh vegetables, and fish, lowers LDL cholesterol by about 10–15%. In most cases, this alone is not sufficient. However, due to its overall healthy composition, it has additional beneficial effects on blood pressure and body weight and should always be part of basic therapy for every person with diabetes.
The Heart Under Pressure
Blood pressure targets are also lower for people with diabetes and should be below 140/85 mmHg. Achieving these targets almost always requires medication in addition to a healthy lifestyle. Each medication is expected to lower blood pressure by about 5 mmHg. Often, multiple medications are needed—frequently 2 to 4 different antihypertensive agents per day.
The benefit of blood pressure reduction is so substantial that this therapy should be carried out very carefully and consistently. Blood pressure medications do not work the same way in every patient, so it is necessary to determine which medication is best suited for each individual. It can take up to four weeks for blood pressure therapy to become fully effective, as the body needs time to adapt to the changes. Regular medication intake is therefore essential for effective hypertension treatment. Blood pressure control also plays a key role in stroke prevention.
The “Sweet” Heart: Blood Glucose and Blood Vessels
Optimizing blood glucose plays a secondary role in reducing vascular risk in people with diabetes. However, there is general agreement that the HbA1c value should be kept below 7.5% in the long term. The evidence base is still unclear, and many renowned researchers believe that a significantly lower HbA1c level of around 6.5% substantially reduces cardiovascular risk.
In any case, if coronary heart disease is present, the HbA1c target should be kept as close as possible to below 6.5%, provided there are no other reasons that would argue against this.