Coronary heart disease and diabetes are two of the most prevalent chronic diseases worldwide.

Both diseases are linked, with diabetes being a significant risk factor for the development of CHD.

CHD is the leading cause of death worldwide, accounting for 16.5 per cent of all deaths in 2019.

Diabetes is also a major public health problem, with an estimated 463 million adults living with the condition in 2019. The prevalence of diabetes is expected to rise to 700 million by 2045.

The coexistence of CHD and diabetes is common, with approximately 20 per cent to 40 per cent of patients with CHD having diabetes.

How can diabetes affect the heart?

In several ways:

∎ One significant mechanism is the development of insulin resistance, which is a hallmark of type 2 diabetes. Insulin resistance leads to endothelial dysfunction, which is a precursor for the development of atherosclerosis, or plaque build-up in the coronary arteries. In addition, it can lead to rigid blood vessels and hypertension.

Insulin resistance also promotes platelet activation, making them “stickier” and more prone to clotting. A meta-analysis of 20 studies including 95,783 participants found that insulin resistance was associated with a 44 per cent increased risk of coronary disease.

∎ Another mechanism is chronic high sugar or hyperglycaemia, which promotes the formation of advanced glycation end products. AGEs can cause oxidative stress and inflammation, both of which can contribute to the development and progression of atherosclerosis. AGEs also promote the cross-linking of collagen fibres in the blood vessels’ wall, leading to their stiffening and again to hypertension.

A meta-analysis of 16 studies including 7,341 patients with CHD found that elevated levels of AGEs were associated with a 51 per cent increased risk of cardiovascular death.

∎ Via multiple means, diabetes can also lead to negative structural changes in the left heart chambers, called adverse remodelling, which can lead, in the long run, to atrial fibrillation and heart failure. A meta-analysis of 28 studies including 57,195 patients found that diabetes was associated with a 71 per cent increased risk of heart failure compared to patients without diabetes.

∎ Diabetes can also cause hyperlipidemia, or high cholesterol and triglycerides, another notorious cardiac disease risk factor.

Can diabetes worsen the severity of heart disease?

Diabetes can lead to a more severe form of heart disease. This relationship gets stronger as diabetes gets more long-lasting and less controlled.

Patients with diabetes are more likely to have multiple coronary vessels disease, diffuse atherosclerosis, and small or microvascular disease, all of which contribute to higher morbidity and mortality. In fact, diabetes is associated with an increased risk of recurrent heart attack [25 per cent to 35 per cent more than when diabetes is absent], stroke [30 per cent], and heart failure [35 per cent].

Consequent to all that, patients with diabetes are also more likely to require cardiac procedures, such as stenting or coronary artery bypass surgery, and have a higher risk of perioperative complications.

How to care for yourself

∎ Lifestyle modifications

Regular physical activity; a low-sugar, low-fat, low-salt diet; smoking cessation. These measures can help to improve blood sugar control, cholesterol and triglycerides levels, blood pressure profile, and excess weight.

∎ Sugar control

The American Diabetes Association recommends an HbA1c target of less than 7 per cent for most adults with diabetes. Treatment strategies with insulin and/or tablets should be individualised, and should take into account the patient's age, comorbidities and medication use.

∎ Blood pressure control

Hypertension is a common risk factor seen in patients with diabetes and heart disease. Patients should be advised to monitor their blood pressure regularly and aim for a target of less than 130/80 mmHg, using above lifestyle measures, a low-salt diet, and quite often blood pressure drugs.

∎ Lipid management

Statins are the first-line therapy in patients with diabetes and heart disease, although other medications, such as ezetimibe or PCSK9 inhibitors, may be necessary for patients who are unable to achieve their lipid goals with statins alone.

∎ Antiplatelet therapy

As mentioned, patients with diabetes and heart disease are at increased risk of clotting events. Antiplatelet therapy, such as aspirin, may be necessary to reduce the risk of recurrent heart attack, stroke or leg ischemia, all being secondary to blood clotting in the heart, brain or lower limbs.

∎ Cardio-renal protective therapy

On top of aspirin and statins, studies have shown that further protection of the heart, the brain and the kidneys from the adverse effects of diabetes, could be achieved using three additional classes of medications: ACE inhibitors, SGLT-2 inhibitors and GLP-1 agonists. These are all prescription drugs and should be adapted according to each individual patient.

∎ Cardiac tests and procedures

Patients with diabetes and established cardiac disease or active risk factors, may require heart diagnostic tests that are more advanced and possibly more frequent than other groups of patients. These tests may unravel heart disease and could lead to procedures like stent(s) or heart surgery, in order to improve coronary vessels patency and overall cardiac pump performance, and reduce the future chance of heart attacks and failure.

Joseph Yammine is a consultant cardiologist at the Bermuda Hospitals Board. The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician