Diabetes particularly type 2 diabetes has been increasing in prevalence worldwide. In Jamaica 11.9 per cent of our population above the age of 15 have a diagnosis of diabetes. Diabetes increases the risk of heart disease, and cardiovascular disease is the most common cause of death for the diabetic patient.

Diabetic patients have an increased risk of atherosclerotic disease (that is laying down cholesterol in arteries) and the risks of stroke, coronary artery disease/heart attacks and peripheral vascular disease are all increased in the diabetic population. In addition, diabetics have been shown to an increased risk of heart failure that is not related to atherosclerosis. Given these findings a diagnosis of diabetes suggests the need to find measures to ameliorate these risks. Early studies looking at the treatment of diabetes suggested that lowering of the blood sugar levels over time decreased the likelihood of some of the complications of diabetes. These included the risk of eye disease, kidney disease and nerve disease. Interestingly, these studies did not demonstrate a reduction in the risk of cardiac and vascular disease despite improved diabetic control. Studies found that treatment of hypertension and high cholesterol in the diabetic patient reduced the risk of developing heart disease and for many years this was the primary focus of risk reduction. However, over the past five to 10 years new medications to lower blood sugar have been shown to improve outcomes and to reduce the risk of heart disease.

The improvement in the efficacy of medications available for treatment of diabetes can be traced back to 2008 when the Food and Drug Administration (FDA) in the United States changed the criteria for the approval of medications for diabetes. Prior to this date, it was enough to show that a medication improved glucose control. The experience with rosiglitazone, a medication which effectively lowered blood sugar but at the cost of an increased risk of heart attack and worsening of heart failure, lead to a change in the way in which medications for diabetes were approved. After 2008 companies developing new medications for diabetes needed to show that medications not only lowered blood sugar but that they did not worsen cardiovascular morbidity and mortality. Several classes of medications have been approved under this new standard with the last two groups: the glucagon like peptide agonists (GLP1 agonists) and the sodium glucose co-transport 2 inhibitors (SGLT2 inhibitors) demonstrating the ability to significantly improve cardiac outcome in patients with diabetes.

Currently, physicians who are treating patients with diabetes have several modalities to improve cardiac and vascular outcomes including lifestyle measures, management of additional cardiac risk factors and the use of diabetic medications with the ability to reduce death and disability from cardiac and vascular disease.

Lifestyle measures

All diabetic and cardiac societies advise lifestyle measures for the general population as well as for those diagnosed with diabetes. There is good evidence to suggest that lifestyle measures can help prevent abnormal glucose handling in the body and thus reduce the likelihood of the development of diabetes. Lifestyle measures can also significantly reduce the incidence of associated conditions that worsen cardiac and vascular outcome in the diabetic patient as well as improving outcome in those diabetic patients with heart disease. Dietary measures and exercise have been shown to reduce the incidence of patients with abnormal blood sugars going on to develop type 2 diabetes. They also reduce the risk of hypertension, hyperlipidemia and obesity which increase cardiac risk in the diabetic patient. Studies have also suggested that in patients with established heart disease (including diabetics) diet and exercise can improve cardiac outcome.

Cigarette smoking is one of the most important causes of avoidable death worldwide and significantly worsens the risk of heart and vascular disease in the diabetic patient. From the point of view of the heart and blood vessels any amount of smoking (even second-hand smoke) serves as a spur to vessel damage and the laying down of cholesterol in arteries. Obesity is prevalent in the Jamaican population (55.5 per cent of Jamaican adults). Obesity not only increases the risk of type 2 diabetes itself, but also increases several cardiac risk factors and the incidence of heart disease including heart failure and coronary artery disease. Good sleep hygiene, avoiding/limiting alcohol, not using illicit drugs and stress management all play important roles in improving long term cardiac and vascular outcome in all populations including diabetics.

Treatment of hypertension in diabetes

Hypertension and Diabetes (particularly Type 2 diabetes) frequently coexist. They have several risk factors in common including obesity, inactive lifestyle, family history etc. They also have several shared hormonal and metabolic abnormalities. Hypertension is twice as common in the diabetic population as compared to the general population. Hypertension and type 2 diabetes together increase the risk of increase heart enlargement, stroke and heart failure more than either condition alone. Many studies have demonstrated the importance of treating hypertension to reduce risk, with greater benefits being noted in the population with type 2 diabetes. One study found that lowering the systolic blood pressure by an average of 5.6mmHg lowered the risk of cardiovascular death by 18 per cent. A large meta-analysis of studies including approximately 79000 patients found that lowering the systolic blood pressure to less than 130 mmHg lowered the risk of stroke by 39 per cent. Evidence has been found that treating hypertension in diabetic patients lowers the risk of severe kidney disease, heart failure, eye disease. Most major diabetic societies suggest targeting blood pressures less than 130 systolic and less than 80 diastolic to improve outcome.

Treatment of high cholesterol in diabetes

Cholesterol abnormalities are common in diabetes. The most common findings are an increase in the triglycerides and a lowering of the HDL (good cholesterol). The LDL (bad cholesterol) is usually not significantly elevated but the type of LDL particles that are found in the diabetic patient may be more likely to result in heart and vascular disease. There is a substantial body of evidence that using statin drugs in diabetes improves outcome. There is some debate among the cardiac and diabetic societies as to when to treat, how aggressively to treat and what the goals of treatment should be. In general diabetics between the ages of 40-75 with risk factors for vascular disease or established vascular disease should be on statin therapy. The American College of Cardiology and the American Diabetes Association propose that all diabetes between the ages of 40-75 should be treated regardless of baseline cholesterol.

In our next article we will look at the impact of diabetic medications on the cardiovascular outcome of the diabetic patient.

Dr Ernest Madu, MD, FACC and Dr Paul Edwards, MD, FACC are consultant cardiologists for the Heart Institute of the Caribbean (HIC) and HIC Heart Hospital. HIC is the regional centre of excellence for cardiovascular care in the English-speaking Caribbean and has pioneered a transformation in the way cardiovascular care is delivered in the region. HIC Heart Hospital is registered by the Ministry of Health and Wellness and is the only heart hospital in Jamaica. Send correspondence to info@caribbeanheart.com or call 876-906-2107.