ACE Inhibitors (angiotensin-converting enzyme inhibitors) are medicines used commonly in the treatment of high blood pressure. They work by blocking the action of a chemical called an angiotensin converting enzyme. This enzyme causes the muscles surrounding blood vessels to contract, thus narrowing the blood vessels. It is harder for the blood to flow through narrow blood vessels and consequently the blood pressure rises. By stopping this enzyme working the blood vessels are allowed to dilate (open) and so the blood pressure is lowered.
High blood pressure (hypertension) is both a risk factor and a complication of diabetes and it poses a greater threat to people with diabetes than it does to people without diabetes. This is because high blood pressure is one of the major factors influencing the development of nephropathy (damage to the kidneys). People with diabetes who have high blood glucose levels are at a greater risk of nephropathy because of the damage high blood glucose levels can do to the small arteries and nerves which supply the kidneys and bladder.
Controlling high blood pressure is, therefore, very important in people with diabetes in order to reduce the risk of developing complications. Even if nephropathy has started to develop, controlling blood pressure can substantially slow its progression. To try and prevent such damaging effects, the blood pressure reading should normally be kept at or below 130/80 mmHg.
ACE Inhibitors have been shown to not only help lower blood pressure but also delay the onset and the progression of nephropathy in people with Type 1 diabetes. In fact this ability to protect the kidneys from damage seems to be their most important quality, more so than their ability to actually control blood pressure. They are as effective as other tablets in controlling blood pressure but it is the added benefit of protecting the kidneys which makes them so important to someone with diabetes.
Small doses of ACE Inhibitors can be given to protect the kidneys in people with Type 2 diabetes who have normal blood pressure and no kidney damage, without the side effect of lowering the blood pressure.
The presence of protein in the urine (microalbuminuria) is an indication that kidney damage has started. People with diabetes should have their urine checked for protein at least once a year at their annual review. When there is only a small amount of protein in the urine the kidney damage is treatable but, if left unchecked, will get worse and lead to serious complications. ACE inhibitors can be used at this early stage of kidney damage, even if the person is already on another type of medicine for their high blood pressure.
ACE Inhibitors include Captopril, Enalapril, Lisinopril, Perindopril, Trandolapril and Ramipril. All need to be started very carefully, in small doses, and then increased to achieve the best effect for the individual. The blood pressure and urine should be checked three to six monthly to ensure there is no further kidney damage. Blood tests should be used to monitor any deterioration of kidney function and ensure potassium levels in the body remain satisfactory.
ACE Inhibitors should be avoided during pregnancy and in people who have already developed renovascular disease (damage to the blood vessels supplying the kidneys). Possible side-effects of ACE Inhibitors can include a persistent dry cough, low blood pressure, dizziness, headaches, abnormal taste (metallic or salty) and raised blood potassium levels - though not all people will experience these.