Low Carb Diets and Type Two Diabetes Mellitus (T2DM) – Should I Make the Switch?

In recent years, low carbohydrate (low carb) diets have gained huge popularity in the media, mainly promoting its benefits for weight loss. Now, this trending diet has become popular amongst those with type 2 diabetes mellitus (T2DM) in an effort to manage blood glucose levels (1). But what exactly is a low-carb diet, and is the trend worth the hype? In this article, we’ll explore low-carb diets and T2DM, what the research says, key considerations, and if there’s any benefit to low-carb for management of diabetes type 2.

In this article you will learn:

• What exactly is a low carb diet?
• What is the definition of a low carb diet?
• What does the research say on low carb diets and T2DM?
• Other key considerations

Just as the name implies, a low carb diet involves restricting carbohydrate foods. Carbohydrates are one of three macronutrients found in the food we eat, and are the major source of fuel used by our brain and body. They are found in a wide variety of foods and contain essential vitamins, minerals and act as a great source of fiber when consumed from whole, unrefined foods (1).

Common sources of carbohydrates that are reduced in a low carb-diet include:

• Fruits
• Legumes and starchy vegetables like potatoes
• Grains e.g. breads, cereals, rice, pasta,
• Dairy products like milk
• Discretionary foods e.g. lollies, chocolate, cakes etc.
• Sugary drinks e.g. soft drink, juice, energy drinks, sports drinks

When following a low carb diet, you naturally consume more proteins and fats – the other two major macronutrients found in food – from foods like meat, chicken, eggs, oily fish, avocados, nuts and oils etc. as well as non-starchy vegetables, for example zucchini, cauliflower and leafy greens.

There’s no standard approach or definition of what a ‘low carb’ diet is. There are so many different types of low carb diets, all with varying levels of restriction. However, when referring to the literature, carbohydrate diets are commonly categorized as per below (1):

Wondering what a low carb diet may look like across the day? Here’s an example day on the plate when following a low carb diet with less than 130g/day:

Breakfast: Omelette with spinach, tomatoes and mushrooms and sliced avocado

Morning tea: 1 cup raspberries and ½ cup reduced fat Greek yoghurt

Lunch: Tuna salad with ½ cup brown rice

Afternoon tea: 1 handful of nuts and veggie sticks

Dinner: Chicken and vegetable stir-fry with cauliflower rice

When reviewing the literature on low carb diets and T2DM, there is reliable evidence that they can be safe and effective in lowering blood glucose levels in the short term – i.e. up to 6 months, and can offer a number of other health benefits.

For example, in 2017-18, three meta-analyses (the highest level of evidence in research) were published looking at the effects of low carb diets and T2DM, by comparing low carb diets (<45% energy from carbs) vs high carb diets (>45% energy from carbs) (1,2,3,4). The key findings from these studies showed:

• A greater reduction in HbA1c up to 6 months
• Better weight loss outcomes up to 12 months
• A greater reduction in heart disease risk factors e.g. cholesterol, triglycerides and blood pressure up to 2 years (1,2,3,4)
• While this research shows promising short term results, it’s important to note that no benefit was seen after 12 months (1,2,3,4).

Also, the CSIRO have been researching the effects of dietary and lifestyle factors on blood glucose control for several years (5). In 2012, they conducted a large scale 2-year clinical trial with overweight and obese participants with type 2 diabetes, which found a low carb diet was more effective at improving blood glucose, reducing risk factors for heart disease and reducing the need for diabetic medication in comparison to a traditional higher carb, low GI, moderate protein diet (5). Similar results were also found in a more meta analysis published in 2021 in the British Medical Journal (BMJ), which demonstrated a low carb diet was found to be more effective in achieving type 2 diabetes remission, when compared to a traditional higher carbohydrate diet (6).

On the other hand, not all studies have found low carb diets to be superior. For example, a recent systematic review and meta-analysis found that people following a low or very low carb diet did not achieve greater diabetes remission i.e. HbA1c <6.5% without medication when compared to other dietary approaches(7).

Overall, while more research is needed to explore the long-term effects and health benefits of low carb diets, a low carb diet may be a suitable approach to consider in the short-term for the management of type 2 diabetes.

While research has identified several short-term health benefits associated with low carb diets and T2DM, other key considerations must be factored in before adopting this style of eating. Note: If you have type 2 diabetes and would like to trial a low carb diet, it’s important to speak with your diabetes healthcare team, for example your GP, Accredited Practicing Dietitian and Diabetes Educator before making the switch.

These include:

• Risk of hypoglycaemia (low blood glucose) – If you are currently taking any medications such as insulin to manage your type 2 diabetes, it’s important you frequently monitor your blood glucose levels and speak with your healthcare team before making changes to your diet. Why? If you’re medications aren’t adjusted and you reduce your carbohydrate intake, you are at higher risk of experiencing hypoglycaemia.
• Possible side effects – As carbohydrates are the body (and brains) major source of fuel, you may experience negative symptoms such as tiredness, headaches and nausea.
• Constipation – Carbohydrates are a major source of dietary fibre, and when reducing these in your eating plan, you may find it difficult to maintain regular bowel motions.
• Possible nutrient deficiencies – Because low carb eating can restrict both energy and carbohydrate sources, nutrient deficiencies can occur if the diet is not well planned or balanced. This can increase the risk of infections, osteoporosis, heart disease and cancer (1). Seek advice from an Accredited Practising Dietitian for a nutritionally adequate plan.
• Adherence and sustainability: As with any restrictive diet, a low carb diet may be difficult to stick to in the longer term. When making changes to your everyday eating plan, it’s important to find an option that fits with your current lifestyle, is enjoyable and is also culturally appropriate.

Type 2 diabetes is a complex medical condition and there is no one-size-fits-all approach. While a low carb diet can offer several health benefits such as improved glucose levels and HbA1c, weight loss and improved heart health, other factors need to be considered to ensure the eating plan you follow is safe, enjoyable, and easy to sustain in the longer term based on your lifestyle.

Diabetes type 2 can be managed in several other ways, for example with a low GI, high protein and high fiber diet, Mediterranean style of eating and more. At Diabetes Wellness Australia, our Accredited Practicing Dietitians take a personalized approach with each and every client to help you find the best approach that manages your condition, whilst working with your lifestyle. If you’re interested to gain insights into the experiences of our valued clients, we encourage you to read Diabetes Wellness Australia reviews.

If you’re looking to take control of your type 2 diabetes and improve your wellbeing, book your free assessment to learn more about our programs and to speak to one of our friendly staff today.