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Can a low-carb diet help manage diabetes?

There’s no doubt that dietary changes are an effective first-line approach for diabetes management—and a low carb diet is one of the most popular choices. 
Annabel Nicholson
11/26/2021
8
min read
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Quick summary

  • Evidence emerging from the scientific community is consistently finding that a low-carb diet is both safe and effective in the short term for most people with type 2 diabetes.
  • A low-carb diet restricts total carbohydrate consumption to less than 130g a day and its important to include complex carbohydrates as part of a healthy diet.
  • A low-carb diet can lead to weight loss, help manage type 2 diabetes, and may lead to type 2 diabetes remission.

To carb or not to carb (and how many carbs to eat) is a common dilemma for people with diabetes, as there are wildly different opinions about whether or not carbs are healthy for people with type 2 diabetes. Often branded the villains of the food world, carbs get a bad rap when it comes to weight management. There’s no denying that carbs are delicious and while sweets and pastries perhaps aren’t the best way to go about a weight loss journey, they aren’t all bad guys. That being said, for people with diabetes it’s worth understanding how carbohydrates can impact blood sugar. There’s no doubt that dietary changes are an effective first-line approach for diabetes management—and a low-carb diet is one of the most popular choices. 

Carbs exist in most diets, in varying quantities

Tucked away in most of our favourite foods are carbohydrates. They take centre stage in a lot of diets and are a hotly debated topic. Of the three main building blocks of food, carbs are the ones that have the biggest impact on blood sugar levels.

There are two main types; Simple (aka sugars, found in pastries, fruit juices, cakes, biscuits, white bread, white pasta, white potatoes) and complex carbohydrates (aka starches, found in whole grains such as brown rice and brown bread, lentils, root vegetables, bananas). It’s easy to fall into the trap of assuming that sweet things are bad for us, but both sugary and starchy carbohydrates all break down into glucose, which then enters the bloodstream and raises blood glucose levels. So, what’s the difference between the two? Essentially, it’s the time it takes for the carbohydrate to get broken down. Simple carbohydrates break down and enter the bloodstream far quicker than complex carbohydrates, causing a rapid spike in blood glucose levels.

For people with diabetes, it’s important to not only acknowledge the impact of all carbohydrates on blood glucose levels, but also to consider taking appropriate action to manage the condition with dietary changes.

So...what’s this about a low-carb diet?

We understand that the word ‘diet’ can have a lot of different meanings, and for many it is often linked to negative, challenging experiences. We don’t believe in branding foods as ‘good’ or ‘bad’ and we don’t believe in exiling a food group ‘just because’. What we do believe, however, is that the food we eat impacts our health. For people with diabetes, this might mean exploring how to lower carbohydrate intake. 

We also believe in listening to science—and the evidence emerging from the scientific community is consistently finding that a low-carb diet is both safe and effective in the short term for most people with type 2 diabetes.[1] So, what does this mean exactly?

A low-carb diet can lead to weight loss

Let’s start with the simplest fact; Consuming fewer carbohydrates can lead to weight loss, and for type 2 diabetes this is an important management tool. 

All carbohydrates are broken down into glucose and absorbed into the bloodstream, but simple carbs do it much more quickly. This can lead to unstable blood glucose levels as the body releases insulin to rebalance, storage of excess glucose not used by cells as fat, and hunger pangs, even after eating a carb-heavy meal.

Aside from adopting a low-carb diet, other effective ways to manage carbohydrate intake are to simply reduce the carbohydrate portion size or opt for whole grains, which significantly reduce and draw out the blood glucose response after eating.[2] Both of these methods contribute to more stable blood sugar levels, which help you feel fuller for longer.

A low-carb diet can help manage diabetes

To ‘manage diabetes’ is to manage blood glucose levels and hopefully stabilise them. The low-carb approach to managing diabetes is preventative. Rather than using medicines to lower blood glucose levels, restrictions on carbohydrate consumption prevents rapid spikes. 

Reducing the intake of carbs, choosing whole grains, and eating smaller portions can all contribute to diabetes management by helping to stabilise blood glucose levels, reducing the body’s need for insulin.

In one study, 25% of participants experienced entry into remission

Musa-Veloso et al, American Journal of Clinical Nutrition

A low-carb diet may lead to type 2 diabetes remission

In some cases, eating a low-carb diet stabilises blood glucose levels and causes enough weight loss that a person can enter remission. In one study, 25% of participants experienced entry into remission.[3] This incredible result is definitely worth celebrating, but it also leads us nicely on to…

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Drawbacks and considerations regarding low-carb diets

You may have noticed that we italicised the phrase ‘in the short-term’ in the section above, and with good reason. Studies indicate that following a low-carb diet for 6 months can lead to the benefits we’ve discussed so far: weight loss, disease management, and, in some cases, diabetes remission. However, one study found that after 12 months, many of these benefits diminished.[1] It’s unclear whether this was because the diet was too hard to maintain for a long stretch of time or for other reasons], but it's a distinct message that highlights a major challenge—a lack of long-term and follow-up studies. Considerably more research is needed to understand the long-term effects of this approach. The results of the above study also flags a potential gap in patient care in terms of ongoing education and support. 

As we’ve already mentioned, in one study 25% of the participants achieved remission.[3] But what about the other 75%? A huge challenge of nutritional research in general is that everyone’s response to diet is unique. We’ve said it before and we’ll say it again—there is no one size fits all, which naturally poses quite the conundrum. That said, 46% of participants lost about 5% of their body weight, and some up to 7%! So even if a low-carb diet doesn’t lead to remission, it can support weight loss, which is a major part of diabetes management. And on the flip side, who’s to say you’re not in that 25%?

How many carbs should I eat daily on a low-carb diet?

The exact definition of a low-carb diet varies but tends to restrict total carbohydrate consumption to less than 130g a day.[4] A very low-carb diet would take this down to just 20-30g a day.[4] To put this into context, a medium-sized slice of bread contains about 15-20g carbohydrate, while a large jacket potato could be as much as 70g.[5]

The bottom line on low-carb diets

There’s compelling evidence to suggest that a short-term low-carb diet can help manage diabetes and perhaps even lead to remission. As with anything to do with dietary diabetes management, our advice remains the same—speak to your medical team and find out what’s right for you, your lifestyle, and your diabetes. Low-carb isn’t for everyone... and remember, low-carb doesn’t have to mean no carb! Despite their effect on weight and blood glucose, complex carbohydrates contain essential vitamins, minerals, and fibre, all of which contribute to a healthy diet.

References

[1] Goldenberg, J. Z, Day, A., Brinkworth, G. D. et al. (2021). Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ 372:m4743. Accessible here.

[2] Musa-Veloso, K., Poon, T., Harkness, L. S. et al. (2018). The effects of whole-grain compared with refined wheat, rice, and rye on the postprandial blood glucose response: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 108(4):759-774. Accessible here.

[3] Saslow, L.R., Summers, C., Aikens, J. E., Unwin, D. J. (2018). Outcomes of a digitally delivered low-carbohydrate type 2 diabetes self-management program: 1-year results of a single-arm longitudinal study. JMIR Diabetes 3(3):e12. Accessible here.

[4] Low-carb diet and meal guide. Diabetes UK. Retrieved 21 July 2021. Accessible here

[5] Carbohydrate reference list. Diabetes UK. Retrieved 21 July. Available here

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