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Type 2 diabetes and cardiovascular disease

Cardiovascular disease (CVD) is the major cause of death and disease in Australia, and in addition, it is the leading cause of death and disability in people with type 2 diabetes mellitus (T2DM).1,2

The burden of CVD among patients with T2DM is substantial; these individuals are four times more likely to develop CVD than healthy populations.2

Yet, this isn’t surprising since the modifiable diet and lifestyle risk factors that contribute to the development of T2DM also contribute significantly to cardiovascular risk.1

This increased risk has recently become more recognised and it is not uncommon for statin therapy to be implemented upon diagnosis of T2DM, regardless of baseline cholesterol levels.2

Considering that diet and lifestyle factors are leading contributors to both conditions, dietary intervention should also be taking a more prominent role in treatment and prevention.

Risk factor: Hyperglycaemia

Hyperglycaemia is less recognised as a risk factor for CVD, yet it is the key predictor of T2DM.1

In patients with uncontrolled T2DM, dramatic fluctuations in blood glucose levels have been shown to trigger an inflammatory response; with the inflammatory response from one short-term episode of hyperglycaemia being shown to last up to several days.3,4

So, ongoing poor glycaemic control can lead to a state of chronic inflammation, with the resulting oxidative stress believed to be the mechanism by which vascular damage begins to occur.5

Dietary preventative measure: Complex carbohydrates

Controlling blood glucose levels should be the number one goal of all patients with T2DM.

From a dietary perspective, a general healthy diet is recommended, with particular emphasis on the consumption of regular meals that include slow releasing, complex carbohydrate foods, such as wholegrain breads, cereals and pastas, legumes, whole fruits, starchy vegetables and low-fat dairy products.

With the exception of low-fat dairy, these foods can also provide a good source of fibre, which is not digested by the body and has a negligent impact on blood sugar levels.

Risk factor: Hypertension

Elevated blood pressure is a well-known risk factor for developing CVD.6 Coincidently, it has also been documented that patients with T2DM are at a higher risk of developing high blood pressure.2,7

Individuals with T2DM commonly experience increased body fluid volume in addition to decreased ability for the blood vessels to stretch.2,7 

Dietary preventative measure: Restrict sodium

Patients with T2DM should be encouraged to not further exasperate their already higher risk by ensuring they follow a diet low in sodium.6,8

Diet has proven to be an effective management strategy, with the DASH diet (Dietary Approaches to Stop Hypertension) specifically being shown to be just as effective as pharmacological intervention.9

The DASH diet represents a reduced-sodium diet indirectly by supporting the consumption of whole foods over processed foods.

This essentially means a diet rich in fruits and vegetables, legumes, nuts, fish, poultry, whole grains and low-fat dairy, with limited fatty meats and processed foods.

In addition, patients should be urged to utilise herbs and spices as a means of flavouring as opposed to salt.

Risk factor: Dyslipidemia

Dyslipidemia, a condition commonly reported in patients diagnosed with T2DM, is another risk factor associated with CVD.4,8

While the exact relationship is unknown, literature suggests that insulin may contribute to imbalance due to its role in regulating lipid metabolism.2

The most common abnormalities in lipid metabolism that are observed in patients with T2DM are increased triglyceride levels and decreased HDL cholesterol levels.2,4,8

These abnormalities play a central role in the development of atherosclerosis, which is six times more likely to develop in patients with T2DM.2,4

Dietary preventative measure: Optimise healthy fat intake

Again, general healthy eating guidelines should be followed.

Patients with T2DM are recommended to follow a dietary pattern with moderate fat — approximately 30–35% of total energy consumed.

The dietary fat should mostly be obtained from foods rich in unsaturated fats that are high in omega-3 — such as nuts and seeds, fatty fish, avocado and olive oil — and should limit saturated fat by choosing lean meat products, trimming visible fat, avoiding palm and coconut oils, restricting highly processed meats and choosing low-fat dairy products.

T2DM and CVD generally coexist as a result of sharing similar risk factors, which tend to be heavily influenced by diet and lifestyle.

A healthy diet rich in whole grains, fruits and vegetables, legumes, nuts, fish, poultry and low-fat dairy, with limited fatty meats and processed foods is strongly recommended as a preventative measure to keep these risk factors at bay.

Alongside their pharmaceutical therapies, pharmacists should encourage patients with T2DM to improve their diet and lifestyle, with referrals to dietitians highly recommended upon initial diagnosis to optimise the benefits of dietary intervention.


Bridget Scrogings, Accredited Practising Dietitian


References:

  1.  Shaw J, Merlin T, Magliano D. The Dark Heart of Diabetes. Baker ID. 2017. Accessed at <https://www.baker.edu.au/-/media/documents/impact/Baker-Institute-The-dark-heart-of-type-2-diabetes>
  2. Diabetes Australia. Heart Disease. 2018. Accessed at <www.diabetesaustralia.com.au/heart-disease>
  3. Pistrosch T, Natali A & Hanefeld M.  Is Hyperglycemia a cardiovascular risk factor? 2011. Diabetes Care 34(2): 128–131
  4. Lee P, Halter J. The pathophysiology of hyperglycaemia in older adults: clinical considerations.  2017. Diabetes Care 40: 444–452.
  5. Davidson J, Parkin C. Is Hyperglycemia a Casual Factor in Cardiovascular Disease? 2009. Diabetes Care, 32(2): 331–333.
  6. Pererira R & Franz M. Prevention and Treatment of Cardiovascular Disease in People with Diabetes Through Lifestyle Modification: Current Evidence-Based Recommendations. 2008. Diabetes Spectrum 21(3): 189–193.
  7. Ohishi, M.  Hypertension with diabetes mellitus: physiology and pathology. 2018. Hypertension Research. 42(6): 389–393.
  8. Watkins P. Cardiovascular disease, hypertension, and lipids. 2003. BMJ, 326:874
  9. Ndanuko R, Tapsell L, Charlton K et al. Dietary Patterns and Blood Pressure in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Advances in Nutrition.  7(1):76– 89.

 

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