www.diabeticretinopathy.org.uk

General

Blood pressure and diabetes

David Kinshuck

 

This page is best viewed printed out. If you are a patient you can take this to your practice nurse so it can be used for ideas.

 

Why do you need a blood pressure of 130/80?

Complications from diabetes develop much more quickly if blood pressure is high. This is illustrated in the graph opposite, from the UKPDS £23 million study. Lifestyle has a major impact on blood pressure, but medication is generally needed.

enlarge see UKPDS 69 and 36 and slides

 

Take control of your blood pressure

If you have high blood pressure, take control. Buy a machine (in Birmingham, Lloyds Chemists sell good machines for ~£15). If your blood pressure is high and you are trying to lower it, check the pressure daily, and keep it below 140. Doctors need to test, and electronic systems can be helpful.

 

'Home Monitoring' blood pressures

 

Blood pressure upper targets, the lower the better
clinic home monitoring  
130/80 125/75 general;  ambulatory night time BP <120
130/80 120/75 with retinopathy
125/75 120-115/70 with proteinuria
115/..... 105/... to prevent deterioration in renal function (ideal), as long as there are no side effects

 

 

White coat hypertension: fluctuating blood pressure

There is a considerable risk of stroke in this condition. Many people say their blood pressure is normal at home or at their doctor's, but high in the eye clinic. Such fluctuating blood pressures are still harmful, indeed twice as harmful as regular hypertension. Lancet 2010    Masked blood pressure.

 

Proteinuria and blood pressure

www.kidney.org.au

 

If your kidneys are leaking protein, you need a low cholesterol (<5.12 mmol/L), triglycerides (<1.64 mmol/L), blood pressure (<115 systolic), and HbA1c (<8%). This is reviewed here or here. If you can achieve low levels, then your kidney function may not get worse. If you cannot achieve these levels, and you have protein in your urine, your kidney function may slowly get worse. Even lower blood pressures help further, see here.

 

NSAI (eg ibuprofen) puts blood pressure up

 

NSAI (non-steroidal anti-inflammatory) drugs, such as ibuprofen (eg Nurofen), are not recommended for long term use. They increase blood pressure.

 

How can you lower your blood pressure?

No one is telling you what to do, and your lifestyle is largely under your control (unless you are disabled). But a healthy lifestyle is essential if you want to keep your sight and your kidneys. Your doctor can arrange for help for you to stop smoking, and help if you are alcoholic.

Professionals are there to help when they can, but if you have no arthritis yet decide not to walk for 30 minutes a day, inevitably your health will suffer. 2 hours a day is the ideal time spent exercising if you are overweight, 1 hour if not. You may need 4 different tablets to lower blood pressure, as below. Lifestyle factors.

 

Exercise such as walking or swimming, 30 minutes a day
salt Not adding much to food, and reducing amounts of processed food with salt already added. Afro-Caribbeans are very salt sensitive, so reduction is important.
smoking  20/day triples the likelihood of problems from diabetes
losing weight exercise more and eat less. Losing 10% weight will cause a marked reduction in blood pressure
alcohol contributes to high blood pressure: stick to less than 2 units/day. Each unit = 2.2 mmHg blood pressure.
a healthy diet helps in the long term, as does a cholesterol less than 5.0. Red meat increases blood pressue 1.2mmHg. Omega 3's are helpful. Flavenoids
some drugs put blood pressure up non-steroidals put blood pressure up e.g ibuprofen
Kiwi fruits lower Bp

 

What is your blood pressure?

keep a record of your blood pressure

 

Keep a record. Why not carry the details with you for all your nurses and doctors to see? The most accurate pressure is that measured by your practice nurse. Results are higher when taken by doctors! Generally it is not considered necessary to test your pressure at home with your own machine, but it can be very helpful. Do not worry if you cannot reach the ideal blood pressure of 130/80 or below. Some people, particularly if you have lots of medical problems, may not be able to reach such a blood pressure. Discuss this with your doctor or nurse.

 

When are blood pressure checks needed?

diabetes blood pressure complications graph

Each 10 mmHg rise in blood pressure causes and extra ~12% deterioration in retinopathy & kidney damage.

 

If you have high blood pressure and you are working with your doctor and nurse trying to lower it, a test every 2-6 weeks is helpful. Naturally tests should be more frequent if it is very high, or you need it very low because of your eyes.
Similarly, if you are well and your pressure is low (especially children), every 3-6 months is fine. Keeping your pressure low slows down the development of other problems that you may get with diabetes such as eye, feet, kidney, nerve, and heart problems.

So the lower your blood pressure the better, and this will delay needing laser for retinopathy, or, if you are already having laser, the laser is more likely to be effective.

 

Salt and Blood Pressure

Some people with high blood pressure can achieve a lower blood pressure by reducing salt  intake. The difference occurs because people have different metabolisms, and these may be genetically determined by the genes you have inherited from your parents. (Salt sensitivity, review).   33% salt reduction from the current average level would reduce blood pressure 4mmHg (NEJM 2009..but this is an average, it will be much more in some people).

Sources of salt in our diet
15% of contribution from salt natural in fresh food
15% of contribution from salt what we add at the table
70% of contribution from salt from convenience and processed food, most of which have salt added
Amount in processed food
1% of the foods content in cereals, such as corn flakes
>2% of the foods content vegetarian canneloni (tesco's); Special K cereal

If you eat food with a lot of salt it tastes awful without....... for about 4 weeks, after which you should get used to the new taste. Then the food you used to like will taste salty! This is not like cigarettes, which can be very difficult to stop.

 

General advice...the blood pressure control cycle

continuous cycle of blood pressure control

 

A healthy lifestyle delays the development of high blood pressure. However, even with the healthiest lifestyle, and perhaps partly because of genes you have inherited from your parents, most people with diabetes develop high blood pressure eventually. At this stage drugs are needed to lower the pressure to prevent complications (as above).

If you start a new drug, and it makes you feel very ill, stop it right away and see your doctor. If you notice an effect that is not so serious, read the drug information leaflet with the drug. Some side effects are specific to the drugs, and some of these are mentioned below. Some are more general, such as dizziness when you stand up.

 

Compliance and blood pressure medication

Compliance improves if the drug treatment is explained. Compliance is normally about 50%. Simply prescribing the medication is not sufficient. Patients need to know a little about the drugs, how they work, and why they are needed.

A stepped approach is helpful as below. Patient educational status, belief in taking the drugs, and encouragement by the family were important. A training program for doctors helps!

 

Which drugs are best...a traditional protocol

 

A treatment plan

 

Drug step 1 Precaution Details
  • ACEI or ARB started
    Dose increased gradually as below, according to the drug. BMJ 2011  All patients <55y.
    U+Es checked the next week.
  • If ACEI not well tolerated, stop and replace ACEI with ARB
  • Afro-Caribbeans and patients >55y    calcium channel blocker first
  • thiazides if oedema present or heart failure
  • Start if foot pulses are present. Foot pulses indicate renal artery stenosis is unlikely.
  • ACEI/ARB if pregnant.
  • Genes make a significant contribution.

step 2 add another in the group Precaution Details
  • calcium channel blocker
  • ACEI or ARB
see above

step 3 add Precaution Details
  • thiazide such as Bendrofluazide 2.5mg (or other thiazide).
 

step 4 add Precaution Details
  • further diuretic
  • or if potassium <4.6, spironolactone 25mg od (increasing to 50mg od). 
  • or selective beta-blocker
    such as atenolol 25-50mg OD
  • or alpha-blocker, such as doxazosin
  • later ? bendrofluazide with frusemide
  • add other drugs, possibly in combination. Loop diuretics such as frusemide if renal function reduced.
  • Aliskiren

Renal function

  • if eGFR <30ml/min/1.17m2 use loop diuretic
  • if>30 use thiazide

 

Side Effects

The vast majority of people taking tablets for high blood pressure feel perfectly well and have no side effects from the tablets. Their only problem is remembering to take the tablets! After starting new treatment it is only natural to think that any new symptoms must be caused by the treatment. If you do seem to have side effects, discuss them with your doctor who will be able to tell whether or not the tablets are to blame.

Most of the tablets for treating high blood pressure can also be used for other heart conditions. So don't be surprised or worried if you know someone with a different condition who is taking the same tablets as you. Naturally medication should be stopped if you are sure it is making you ill, and discuss problems with your doctor.

 

sore or watery eyes Blood pressure tablets may make these worse, especialy furosemide.
other tablets Possible reaction with other tablets, including some that are available without a prescription, including herbal remedies. Check with your doctor or pharmacist before you take them.
Rash May develop soon after you start a new treatment. Report this to your doctor. You may have developed an allergy to the tablets.
light-headed or dizzy  If you feel, or if you faint. These effects may be particularly noticeable when you get up from bending or lying down, or if you are older.
If these side effects are severe, it may be that your tablets have reduced your blood pressure too much.
Tell your doctor who might reduce the dose of the drug or give you different tablets.
potassium ACEI inhibitors and ARBs can cause high potassium levels, andthis is much common is there are kidney problems. Potassium levels should be checked one week after starting or increasing dose.

 

ACEI inhibitors and ARBs

 

  • ACEI examples
  • Angiotensin receptor antagonists (ARBs) examples
  • valsartan
  • candesartan  (DIRECT)
  • irbesartan can be used in the presence of renal and moderate liver failure, 150-300mg day)
  • Blood tests
  • immediately before treatment
  • 7-10 days after starting
  • regularly thereafter
  • if dose increased
  • intercurrent illness

ACEI stands for 'angiotensin converting enzyme inhibitors'; they work by stopping the conversion of an inactive substance in the blood called angiotensin 1 to the very potent angiotensin 2, which produces spasm and constriction of the blood vessels.
Angiotensin receptor antagonists  (ARB, also called angiotensin II inhibitors) are likely to be just as effective as ACEI inhibitors (ACEI).

Patients using ACEI and ARBs need monitoring with U & Es (kidney function and electrolytes) tests. They work partly by making the walls of the arteries relax and dilate. The first dose can cause quite a large drop in blood pressure, so this dose is best taken last thing at night.
You should not take ACEI inhibitors if you are pregnant.

ACEI & ARB are generally recommended for diabetes, even if there is no hypertension (see). They reduce progression rate 50% in some studies. This may be because there are angiotensin receptors in the retinal cells.

 

Unwanted effects of ACEI/ARB

ACEI/ARB are generally better tolerated by patients than most of the other drugs. However, they can cause a marked fall in blood pressure, especially when first used by people who are also taking diuretics. They may also affect the function of the kidneys if this is already abnormal. When your doctor starts the treatment, they will take care to start you on a low dose and will regularly check your blood, as above.

Some ACEI may affect your sense of taste and cause skin rashes and, very occasionally, a major allergic reaction. Some people develop a persistent, dry, irritating cough. If this happens, you should tell your doctor about it.

ARBs are generally better tolerated, although some are more expensive. Also, whilst much research has identified the benefit of ACEI, there is less evidence about ARBs. However, concerning blood pressure and diabetes, they are generally felt to be as effective.

 

Types of calcium channel blockers

Calcium channel blockers

May cause ankle swelling. These are now usually added to patients already taking ACEI/ARBs

 

Thiazide diuretics

These are common drugs, now usually added when patients are taking ACEI/ARB and calcium channel blocker. They were previously first line treatment in non-diabetics. Very low doses (such as bendrofluazide 1.25mg) may be better, but at present these are only available as combination drugs. The doses opposite may increase blood fat levels, sugar levels, uric acid, and lower potassium levels. These are often known as the 'water pills'. They work on the kidneys, helping them to pass more salt and water into the urine. This triggers hormone reactions which lower the blood pressure. If passing water too much makes your life difficult or leads to incontinence, tell your doctor.

Altogether there are three types of diuretics. These are: thiazide, loop diuretics, and potassium-sparing diuretics. If you take a thiazide or loop diuretic, your doctor will arrange a blood test a few weeks after you start, to check the potassium level in your blood. If this is getting low, you will be given potassium supplements, or a potassium-sparing diuretic will be added. If you are diabetic, you may find that diuretics raise your blood sugar levels.

Loop diuretics include frusemide or bumetamide, and are especially useful in diabetic nephropathy, often combined with an ACEI inhibitor.

 

Spironolactone

If potassium <4.6, spironolactone 25mg od (increasing to 50mg od). This can give breast tenderness and gynaecomastia: if this happens substitutes are available. If more than 3 drugs are needed, this is classified as 'resistant hypertension' BMJ 2012, NICE 2011.

If potassium >4.5, increase the dose of thiazide diuretic

 

Beta blockers

 

suggested drugs
  • atenolol 25-50mg day
expect
  • help with angina, tired, fatigue, cold hands & feet
unwanted / not recommended
  • increase insulin resistance and change fat levels
  • asthma patients
  • very slow heart beat; aim for a pulse rate of over 45 beats a minute
  • impotence (poor erections)
  • Very cold hands and feet etc
  • nausea, diarrhoea, skin rashes, nightmares, and pins and needles in the fingers.

These are also first line agents in non-diabetics. Beta-blockers as a whole are less effective in Afro-Caribbeans. They work by stopping the action of adrenaline. This reduces the pulse rate and limits the amount the pulse rate rises when you exercise.

Serious side effects are rare if beta-blockers are used with care. Beta-blockers should not be stopped suddenly without medical advice. If you also have angina, stopping beta-blockers too quickly can make it worse. If you have diabetes, you need to be aware that beta-blockers may suppress the usual warning signs of low blood sugar - such as palpitations and tremor. If you stop taking beta-blockers, you may feel as if your heart is beating abnormally fast or heavily (palpitations). Ask your doctor for advice if this continues.

Vaso-dilating beta-blockers may be preferable see.

 

Last

Other drugs include those acting centrally on the brain, such as physioten, or doxazasin.

 

Monitoring

The effect of drug treatment may take 2 months to be apparent. But if there is severe retinopathy with significant hypertension 1-2 week follow up may be best, to check for side effects and that the blood pressure is dropping.
Once stabilised, BP can be checked every 3-6 months. Electrolytes should be checked prior to drug treatment. If diuretics are used then potassium should be checked after 4 weeks treatment. Special monitoring is required for ACEI inhibitors.

 

Studies