Diabetes increases heart risks

People with diabetes have an increased risk of developing cardiovascular (heart and blood vessel) disease, particularly atherosclerosis, where the arteries become narrowed by a build-up of fatty deposits. Atherosclerosis is also known as 'hardening' of the arteries, and increases risk of blood clots, heart attack and stroke. Keeping your blood glucose and blood pressure at recommended levels, eating healthily, having regular exercise and not smoking are lifestyle measures which will help reduce risk. Medications may also be needed if blood fats such as cholesterol remain at high levels. 

Cholesterol can narrow arteries

Cholesterol can accumulate in the walls of the major arteries supplying the heart, brain and sometimes the leg. This cholesterol build-up narrows the artery, decreases blood flow and can sometimes rupture and block the artery.

Atherosclerosis is accelerated by high blood cholesterol levels, diabetes, high blood pressure and smoking.

Healthy blood flow in an artery	Mild atherosclerosis (plaque)
Severe atherosclerosis	Artery blocked by a clot

What are lipids?

Lipid is the term used to describe the fatty substances carried in the blood. These include cholesterol and triglycerides. Cholesterol and triglycerides are transported around the body as lipoproteins.

The main lipoproteins referred to are low-density lipoprotein (LDL cholesterol or the 'bad' cholesterol), high-density lipoprotein (HDL cholesterol or the 'good' cholesterol) and triglycerides. Recommendations are for the LDL cholesterol and triglyceride levels to be kept low as these can damage the arteries, whereas the HDL cholesterol is considered to be protective for the arteries, so should be high. (Also see 'Health targets' further below).

Risk factors for stroke and heart attack

• Diabetes and poor blood glucose control
• Not enough HDL (protective or 'good' cholesterol)
• High cholesterol and triglycerides
• High blood pressure
• Smoking
• Too little exercise
• Excess weight
• Family history of heart disease
• Kidney damage in diabetes (protein in urine or impaired function)

Reducing the risk factors

In addition to ensuring good blood glucose control in diabetes (4 to 7 mmol of glucose per litre of blood, measured before meals), the risk of heart attacks and stroke can be further reduced by tackling as many of the following risk factors as possible:

• Stop smoking
• Aim to achieve and maintain a healthy body weight
• Aim to do some form of regular exercise
• Reduce high cholesterol and triglycerides with a low-fat, high-fibre diet and medication if required.

Weight control, exercise and stopping smoking are also important in raising HDL ('good cholesterol') levels.

Achieve blood pressure control with:

• A diet that is low in saturated fat
• A low alcohol intake
• A low-salt diet with plenty of fruit and vegetables
• Maintaining a healthy weight
• Maintaining good blood-glucose control.

Health targets:

• Total cholesterol less than 4.0 mmol/L
• Triglycerides less than 1.7 mmol/L
• HDL-cholesterol greater than 1.0 mmol/L
• LDL-cholesterol less than 2.0 mmol/L
• Lower levels of LDL are needed in those with established blood vessel damage
• Blood pressure (BP) levels less than 130/80 mmHg [discuss individual target BP with your doctor, younger people may be given lower target].

Dietary guidelines

• Monitor your body weight and waist measurement
• Be physically active
• Aim to eat at least five to eight servings of fruit and/or vegetables daily
• Include some wholegrain foods with two or more meals every day
• Choose low-fat dairy products
• Choose lean cuts of meat, remove visible fat and chicken skin

Include:

• Fish meals twice a week especially dark fleshed or oily varieties. Avoid fried fish
• Legumes or dried beans
• Seeds and nuts except coconut. Use raw walnuts, almonds and peanuts instead of roasted and salted types
• Soy-based foods including soya milk products
• Try using soybeans, tofu, textured vegetable protein in vegetarian style dishes
• Eggs (up to three per week)
• Use small amounts of plant oils and margarines preferably olive oil or canola oil
• Plant sterol spreads can be used
• Use low-fat cooking methods (steaming, microwaving, grilling, rather than frying)
• Choose snacks such as raw fruit, low-fat wholegrain crackers or wholegrain breads with low-fat toppings or fillings, or low-fat yoghurt
• Keep sugary foods and drinks to a minimum
• Keep alcohol to less than two standard drinks for women and less than three drinks for men per day
• Limit salt and salty foods.

Talk to your dietitian about a personal eating plan.

Medication

If lipids (blood fats) continue to be high despite a healthy lifestyle, medication may be necessary. The drugs are in two broad groups:

Statins
Statins include, for example, simvastatin and atorvastatin. Statins can lower cholesterol levels by as much as 40% to 50%. If cholesterol and LDL levels are high, then these are the first treatment choice. They are well tolerated with the most common side effect being muscle ache.

Fibrates
Fibrates modify the composition of the fat particles (lipoproteins). They usually do not lower the cholesterol and LDL cholesterol levels, but they have a powerful effect on reducing triglyceride levels and increasing the HDL level.

Both statins and fibrates are important and very frequently a combination of drugs is needed.

There are additional drug types that may also be used, if suitable for you. Consult your doctor or nurse educator for more information.

Original material provided by Diabetes New Zealand and the Heart Foundation, 2005. Updated by everybody, September 2011.