What are 'carbs' and what is a low-carb diet? Is it necessary for someone with type 2 diabetes?

Low Carb Diabetes Diet

No doubt you’ve probably Googled something along the line of ‘Diet and Diabetes’ since you or a loved one was diagnosed with diabetes. I’m sure the most prominent dietary advice provided by Dr Google was to stop eating carbs… but is Dr Google right?... Are carbs bad news for people with diabetes? Unfortunately, there’s no easy answer to what seems like quite a simple question.

What are carbs?

Carbs are made up of starches, sugars and fibre. Our body breaks down starches and sugars into the most simple form of carb – glucose. Glucose is then transported via our blood, and becomes fuel for our brain, muscles and other organs. Usually, the body is able to regulate the amount of glucose in the blood quite closely, however people with diabetes are unable to control their glucose levels as tightly.

On a side note, fibre (also known as the indigestible part of plants) is not broken down into glucose, which assists in keeping our digestive system healthy, among other roles.

How many carbs do we need?

If carbs raise blood glucose levels, wouldn’t it be better to cut them out completely? Unfortunately, removing all carbohydrate from the diet can be extremely difficult, impractical, and possibly detrimental to health in certain circumstances. The ‘Low Carb Diet’ is a widely debated topic, and contrary to what you may think the evidence for low carb diets is still in its infancy. There is also still scientific debate around what is considered low carb, but currently, the general consensus is less than 130g of carbohydrate each day. Many popular diets can recommend values a lot lower than this, with little evidentiary support, particularly when it comes to managing blood glucose levels.

The amount of carb we actually need depends on our age, gender, physical activity levels and weight loss or weight gain goals. Children should not be placed on a low carb diet to manage diabetes, as this can have detrimental effects on growth, heart health and may cause psychological concerns.

Low Carb diets in type 1 diabetes

There are some short term studies that suggest lowering carbs, may be beneficial in improving glycaemic control (HbA1C%) and reducing insulin requirements. However, these studies are only short term and small.

Certainly, reducing the total amount of carbohydrate can reduce inaccuracies in carb counting, and this may be one of the bonuses of a carb reduction. For example, if you eat a large bowl of pasta with 10% inaccuracy in carb estimate, this is will cause a greater blood glucose fluctuation, then a small bowl of pasta with 10% inaccuracy.

On another note, the literature dose seem to show some improvements in weight management when following a low carb diet. So, if you have Type 1 Diabetes and need to lose weight, this may be an appropriate dietary strategy.

Ultimately, for people with Type 1 Diabetes, until the evidence improves with long term, large trials, it is still recommended that people with Type 1 manage their blood sugar levels with carb counting, and dose meal time insulin accordingly.

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Low Carb in type 2 diabetes

Some people with Type 2 Diabetes may find a low carb diet useful in managing their weight, and this has shown to be effective and reasonably safe, in short term trials. However, like in Type 1 Diabetes studies, there is limited evidence for long term weight management.

The best dietary strategy for weight management is whatever you can stick to. If you think low carb is something that’s easy to follow, helps you lose weight and manage you blood glucose levels, then it could be the right diet for you.

Often, people find it difficult to stick to very low carb diets (ketogenic) and find a more moderate carbohydrate approach is easier (that is around 130g carb each day).

Top tips for Low Carb diets:

  • Low carb diets are not recommended for children to manage diabetes, they can be detrimental to growth

  • It is important to discuss your diet regularly with your diabetes dietitian and doctor, as they can provide you with practical and evidenced based advice.

  • Blood glucose should be monitored closely if you do choose to follow a low carb diet, particularly if you take insulin or other medications.

  • Reducing carbohydrates can have effects on other nutrients, such as fibre, vitamins and minerals, so it’s important to seek professional advice.

This blog is based on the Diabetes UK Position Statement, May 2017.

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