Interventions to manage CVD risk include:
- lifestyle modification
- antihypertensive medication
- lipid-lowering medication
- antithrombotic therapy
- glucose-lowering medications that show novel non-glycaemic effects.
In addition to lifestyle modification, all people at high absolute CVD risk should be treated with both antihypertensive medication and lipid-lowering medication (see below), unless contraindicated or clinically inappropriate.1
GPs should set individual treatment targets for patients, balancing the benefits and risks of interventions. For example, the CVD risk associated with lipid and blood pressure levels is continuous; hence, specific targets are somewhat arbitrary and should be used as a guide to treatment, not as mandatory goals. It is important to understand that there might be small absolute benefits required to reach suggested goals. However, any reduction in risk factor values will be associated with some benefit.1
When developing a management plan for people, refer to the 2023 guideline for assessing and managing CVD risk and the Australian CVD Risk Calculator.
Lifestyle modification
Lifestyle changes in nutrition, physical activity and smoking status underpin a general practice approach to CVD risk minimisation. Lifestyle changes show excellent cost-effectiveness in lowering the burden of disease and remain the basis for the management of all CVD risk levels.10,11
In people with type 2 diabetes and obesity (mean body mass index 36 kg/m2), the Look AHEAD study found that a lifestyle intervention that focused on weight loss improved glycated haemoglobin (HbA1c) and quality of life, but did not significantly reduce the risk of cardiovascular morbidity or mortality.12
For further information, refer to the section ‘Lifestyle interventions for management of type 2 diabetes’.
Antihypertensive medication
Lowering blood pressure reduces cardiovascular events and all-cause mortality in people with type 2 diabetes. Although no difference is noted between different classes of blood pressure-lowering therapy for CVD outcomes, there is clear evidence that in people with type 2 diabetes, antihypertensive therapy with an ARB or angiotensin-converting enzyme inhibitor (ACEi) decreases the rate of progression of albuminuria and retinopathy, promotes regression to normoalbuminuria and may reduce the risk of decline in renal function. Combining an ARB and an ACEi is not recommended.1,13
Blood pressure targets
The target level for optimum blood pressure is controversial. Some international guidelines have changed their blood pressure targets to <140/90 mmHg4,14 whereas others remain at <130/80 mmHg.15 Some suggest that low targets such as <130/80 mmHg could be appropriate for people at high risk of CVD, if achievable without undue treatment burden.14
Considering these guidelines, the RACGP recommends a blood pressure target of <140/90 mmHg for people with diabetes, with lower targets considered for younger people and those at high risk of stroke, as long as the treatment burden is not high.
For secondary prevention of CVD, the target blood pressure for people with diabetes and microalbuminuria or proteinuria (emergent chronic kidney disease) remains <130/80 mmHg. As always, treatment targets should be individualised and people with diabetes monitored for side effects from the use of medications to achieve lower targets.
Lipid-lowering medication
GPs should consider treatable secondary causes of raised blood lipids before commencing pharmacotherapy.
As part of patient centred care, develop a shared decision-making process to decide on optimal therapy including individuals’ preferences and CVD risk calculation. Statins are an appropriate first line lipid-modifying therapy.1 The results from several systematic reviews are consistent, and suggest that people with diabetes gain at least similar benefits as people without diabetes. The data clearly demonstrate that statin therapy results in a significant decrease in coronary artery disease morbidity and mortality in type 2 diabetes for those at high CVD risk.1,16,17 This benefit is in contrast to the contentious effects of improved glycaemic control in CVD risk management.
Statin use for primary prevention of CVD
Statins are indicated for people with diabetes at high absolute risk of CVD, at any cholesterol level.1
Statin use for secondary prevention
Statin therapy is recommended for all people with CVD (unless exceptional circumstances apply).
Other lipid-lowering medications
The evidence for using lipid-lowering medications other than statins to decrease the risk of coronary artery disease is still accumulating. Recent evidence suggests CVD benefit in select subpopulations (see below).
Ezetimibe
Ezetimibe has been studied in the IMPROVE-IT trial in people with diabetes and existing acute coronary syndrome. Compared with a statin alone, ezetimibe combined with a statin showed an absolute risk reduction of 5.5% (40% versus 45.5%) for the composite primary end point of cardiovascular death, major coronary events or non-fatal stroke over seven years.18
Thus, in adults with diabetes with acute coronary syndrome, ezetimibe combined with a statin may provide additional LDL-C lowering (if >1.8 mmol/L on statin therapy and requiring CVD risk reduction).
Nicotinic acid, bile acid resins and fibrates
These agents have been suggested as alternatives for people who cannot tolerate statins.
Nicotinic acid (niacin) was shown in one trial to reduce CVD outcomes, although the study was performed in a cohort of people without diabetes.19 More recent trials have not confirmed this initial result.21 The use of nicotinic acid, in particular, as well as gemfibrozil and cholestyramine, is limited by a high rate of adverse effects.
The role of fibrates (fenofibrate, gemfibrozil) to decrease the risk of CVD is contentious. Fibrates, preferably fenofibrate, should be commenced in addition to a statin or on their own (for those intolerant to statin) when fasting triglycerides are ≥2.3 mmol/L, or HDL-C is low.2
Eicosapentaenoic acid-derived ethyl ester
The Reduce-IT trial of 4 g daily of eicosapentaenoic acid (EPA)-derived icosapent ethyl demonstrated a 25% risk reduction in high-risk people with diabetes on statin therapies who had elevated triglycerides.21 There was an excess of hospitalisation for atrial fibrillation but no associated elevated risk of stroke. The clinical availability of this intervention is still being evaluated in Australia.
PCSK9 inhibitors
PCSK9 inhibitors are injectable lipid-lowering agents that have restricted Therapeutic Goods Administration (TGA) and Pharmaceutical Benefits Scheme (PBS) approval for use in select high-risk patients. They provide potent lowering of LDL-C in addition to other approved lipid-lowering therapies such as statins, ezetimibe and PCSK9-targeted therapies, including monoclonal antibodies and small interfering RNA. Long-term outcome studies on safety for both in class agents are needed. For more information, refer to the TGA and the PBS websites.
Antithrombotic therapy
It is not usually recommended that antiplatelet therapy (eg aspirin, clopidogrel) be used in the primary prevention of CVD. For secondary prevention, the strong positive effects in the conditions outlined in the ‘Table of recommendations’ need to be weighed against individual risks.
Glucose-lowering medications (novel non-glycaemic effects)
In populations with existing CVD, cardiovascular outcome trials have been conducted for newly developed diabetes drugs to demonstrate, primarily, cardiovascular safety and various secondary non-glycaemic endpoints.22 Some trials did include people with multiple risk factors for CVD. The trials were not glycaemic efficacy trials.
Summary of outcomes
Refer below to the individual trial designs and outcomes for specific drug effects.
Sodium glucose co-transporter 2 inhibitors
A 2019 meta-analysis of cardiovascular outcomes trials showed that the use of SGLT2i led to:23
- an 11% reduction in major adverse cardiovascular events, seen only in those with established CVD and not those without CVD
- a 23% reduction in CVD death or hospitalisation for heart failure in those with or without atherosclerotic disease or heart failure.
An updated 2022 meta-analysis evaluating the use of SGLT2i in people with diabetes, with or without other diseases, reported that the use of an SGLT2i over a period of 3.5 years by 1000 people with diabetes and an elevated CVD risk would result in a reduce the number of deaths by nine, major cardiovascular events by nine, hospitalisations for heart failure by 11 and cases of end stage kidney disease by two, but potentially create two cases of ketoacidosis and 36 cases of genital infection.24
The exact mechanism of action of SGLT2i on CVD, chronic kidney disease and heart failure has not been fully elucidated.
Glucagon-like peptide-1 receptor agonists
A 2022 meta-analysis of six RCTs showed that GLP-1RAs reduced the risk of:
- death from cardiovascular causes by 10%
- fatal and non-fatal stroke by 15%.25
A 2023 meta-analysis showed that the use of GLP-1RAs led to:
- a 17% reduction in primary end points for major adverse cerebrovascular outcomes
- a 15% reduction in non-fatal stroke and a 27% reduction in ischaemic stroke, but no reduction in haemorrhagic stroke.26
The exact mechanism of action of GLP-1RAs has not been fully elucidated.
CVD outcomes of combined GLP-1RA/glucose-dependent insulinotropic polypeptide (GIP) agents are yet to be reported.
Dipeptidyl peptidase-4 inhibitors
Recent meta-analyses for dipeptidyl peptidase-4 inhibitors showed that:27–29
- safety, but non-significant benefits for cardiovascular outcomes in those at high risk of cardiovascular events or with established CVD
- a statistically non-significant 5% increased risk of hospitalisation for heart failure with saxagliptin.
Sulfonylureas
Meta-analyses of randomised clinical trials for sulfonylureas have shown:
- no excess cardiovascular risks associated with this class30,31
- lower all-cause and cardiovascular mortality associated with gliclazide and glimepiride compared with glibenclamide.32