Nutrition for type 2 diabetes

This article was written by one of The Food Medic team; registered dietitian – Maeve Hanan

In honour of Diabetes Week 2022, this article will explore nutritional considerations for type 2 diabetes.  

What is type 2 diabetes?

Type 2 diabetes is a medical condition where the body either can’t make enough insulin or the body can’t use insulin properly. As one of insulin’s main jobs is to allow glucose to enter our cells, high levels of blood glucose occur when this hormone isn’t working as it should. 

This is different from type 1 diabetes which is an autoimmune condition where the body attacks the cells in your pancreas which means that no insulin can be produced. Type 1 diabetes is much less common than type 2. 

High blood sugars can lead to short term symptoms like thirst, fatigue and frequent peeing. In the longer term, high blood sugars can damage the eyes, heart, kidneys and nerves. 

There are a number of risk factors for type 2 diabetes including (1):

• family history
• age – the risk increases with age
• ethnicity – with a higher risk seen in African-Caribbean, Black African, or South Asian populations
• certain medical conditions e.g. gestational diabetes, high blood pressure, PCOS, mental health issues
• carrying extra weight around the abdomen 
• sedentary lifestyle
• sleep issues
• smoking
• high alcohol intake 

In the UK more than 4.9 million people have diabetes, and around 90% of cases are type 2 diabetes (2). 

See here for more information about diabetes

Healthy eating

Healthy eating is routinely advised for managing type 2 diabetes, such as The Eatwell Guide in the UK or a Mediterranean-style diet (3). These diet patterns are also recommended to improve health for the general population.

Studies have found that a mediterranean-style diet is linked with a lower risk of type 2 diabetes and improvements in outcomes for those with the condition; such as improvements in blood glucose and heart health (4, 5).  

This eating pattern involves:

• plenty of of fruit, vegetables, whole grains, legumes, herbs, and spices
• consuming olive oil and nuts every day
• 1-2 portions of oily fish per week (e.g. salmon, sardines, anchovies, trout, herring, pilchards, sprats and mackerel)
• a moderate intake of eggs, dairy, and poultry
• water as the main drink
• moderate amounts of red wine
• a low intake of red and processed meat, and foods high in salt, sugar, and saturated fat

Of course, different healthy eating approaches can work for different people with type 2 diabetes based on factors like preferences and lifestyle. 

Diabetes-specific products, like ‘diabetic sweets’ and ‘diabetic chocolate’ are not usually advised, as these can still impact blood glucose levels and can have gut-irritating side effects. 

What about carbs?

Carbohydrates in our food are broken down into simple sugars (mainly glucose) to provide an important energy source for our body. 

But it isn’t necessary for those with type 2 diabetes to avoid carbohydrate because this is still the preferred energy source for the body, and our brian in particular. 

Fibre is also an important type of carbohydrate that is really good for us. Not only is this nutrient key for our gut health, but eating enough fibre is linked with a lower risk of bowel cancer, heart disease and type 2 diabetes (6). Increasing fibre intake has also been seen to significantly improve blood glucose levels for those with type 2 diabetes (7). 

Foods that contain carbohydrates also provide a number of other important nutrients as carbs are found in: 

• starchy foods and grains
• fruit and vegetables
• beans
• nuts
• dairy products

As outlined above these foods are all included in the Mediterranean-style diet which is beneficial when it comes to type 2 diabetes. 

However, different types and amounts of carbohydrates impact blood glucose levels differently. 

The glycemic index (GI) of a food is a measurement of how quickly blood glucose levels increase in response to that food. Lower GI foods lead to a slower increase in blood glucose levels. There’s good evidence that consuming low GI foods is linked with positive outcomes for those with type 2 diabetes, such as improvements in glucose and cholesterol levels (8). 

Examples of lower GI foods include (9):

• multigrain, wholegrain, and sourdough bread
• porridge and oats
• some oat and bran-based cereals (lower sugar versions)
• sweet potato and yam
• new potatoes in their skins
• all types of pasta
• instant noodles
• basmati, brown, or long grain rice
• bulgur wheat
• barley
• quinoa
• couscous
• beans, peas, and lentils

Whereas sugary food and drinks have a high GI.

But the combination of foods a meal or snack is made up of and the portion of food also impacts the blood glucose response to a meal. For example, a balanced meal that contains a starchy food, a high protein food, fibre and fats will lead to a lower rise in blood glucose levels than a starchy food by itself as fibre, fat and protein can all contribute to a lower GI of the meal (10). 

It can also be helpful to spread carbohydrate-containing foods across the day rather than having a bigger portion in one go to help with stabilising blood glucose levels.     

Some people with type 2 diabetes need to use insulin injections or an insulin pump. In this case, counting the amount of carbohydrate in meals and snacks (i.e. ‘carbohydrate counting’) is advised to more accurately calculate the insulin dose needed. 

Weight loss diets

Weight loss is a common recommendation when it comes to type 2 diabetes. This is because fat around the pancreas may hinder the production of insulin and 5-10% weight loss has been linked with improvements in glucose levels and markers of heart health (11). 

More extreme weight loss approaches such as weight loss surgery and very low calories diets that lead to 15kg weight loss have been linked with remission for some people with type 2 diabetes (12, 13). This means that a marker of long-term blood glucose levels called HbA1c stays below the cut off for diabetes without needing diabetes medication for at least six months. 

The longest follow up study we have related to diabetes remission from very low calories diets in 2 years (14). This follow up study shows a number of ongoing improvements, but the percentage of those in remission dropped by over 10% and participants regained roughly 3kg on average over 12 months. So we need ongoing data to determine the long term impact of this approach. It’s also important to remember that this approach is not suitable for everyone (such as those with disordered eating), it involves a lot of input and medical monitoring and doesn’t lead to weight loss or diabetes remission for everyone who tries it. For example, 64.4% of those who followed the very low calorie diet were in remission after 2 years (14). 

Significant improvements to diabetes management can also be made without focusing on weight loss. For example, intuitive eating and mindful eating have been linked with improved management of type 2 diabetes (19, 20).  

Improving self-care and lifestyle factors such as eating well, moving more, getting more sleep and not smoking can all positively impact outcomes for those with type 2 diabetes regardless of weight change. 

Summary

Although a variety of nutritional approaches can be used with type 2 diabetes, the most common approach advised based on the current evidence base is a healthy eating or Mediterranean-style diet. This is the same advice given to the general public in order to support good health. 

Prioritising high-fibre, lower GI sources of carbohydrate can also help with stabilising blood glucose levels. 

Although weight loss can lead to improvements in the management of type 2 diabetes, weight loss diets don’t work in the long term for many people and there are a number of risks related to these. There are also non-weight-focused approaches and habits that can be beneficial and potentially more sustainable for many people with type 2 diabetes.

References:

1. Diabetes UK “Diabetes Risk Factors” [accessed June 2022 via: https://www.diabetes.org.uk/preventing-type-2-diabetes/diabetes-risk-factors]
2. Diabetes UK “Diabetes Statistics” [accessed June 2022 via: https://www.diabetes.org.uk/professionals/position-statements-reports/statistics]
3. BDA Food Factsheet “Diabetes – Type 2: Food Fact Sheet” [accessed June 2022 via: https://www.bda.uk.com/resource/diabetes-type-2.html]
4. Esposito, K., Maiorino, M. I., Bellastella, G., Chiodini, P., Panagiotakos, D., & Giugliano, D. (2015). A journey into a Mediterranean diet and type 2 diabetes: a systematic review with meta-analyses. BMJ open, 5(8), e008222. [accessed June 2022 via: https://bmjopen.bmj.com/content/5/8/e008222.short]
5. Esposito, K., Maiorino, M. I., Bellastella, G., Panagiotakos, D. B., & Giugliano, D. (2017). Mediterranean diet for type 2 diabetes: cardiometabolic benefits. Endocrine, 56(1), 27-32. [accessed June 2022 via: https://pubmed.ncbi.nlm.nih.gov/27395419]
6. SACN (2015) “Carbohydrates and Health” [Accessed June 2022 via: https://www.gov.uk/government/publications/sacn-carbohydrates-and-health-report]
7. Post, R. E., Mainous, A. G., King, D. E., & Simpson, K. N. (2012). Dietary fiber for the treatment of type 2 diabetes mellitus: a meta-analysis. The Journal of the American Board of Family Medicine, 25(1), 16-23. [accessed June 2022 via: https://pubmed.ncbi.nlm.nih.gov/22218620/]
8. Zafar, M. I., Mills, K. E., Zheng, J., Regmi, A., Hu, S. Q., Gou, L., & Chen, L. L. (2019). Low-glycemic index diets as an intervention for diabetes: a systematic review and meta-analysis. The American journal of clinical nutrition, 110(4), 891-902. [accessed June 2022 via: https://pubmed.ncbi.nlm.nih.gov/31374573/]
9. BDA Food Factsheet “Glycaemic Index (GI): Food Fact Sheet” [accessed June 2022 via: https://www.bda.uk.com/resource/glycaemic-index.html]
10. Moghaddam, E., Vogt, J. A., & Wolever, T. M. (2006). The effects of fat and protein on glycemic responses in nondiabetic humans vary with waist circumference, fasting plasma insulin, and dietary fiber intake. The Journal of nutrition, 136(10), 2506-2511. [accessed June 2022 via: https://academic.oup.com/jn/article/136/10/2506/4746688]
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13. Lean, M. E., Leslie, W. S., Barnes, A. C., Brosnahan, N., Thom, G., McCombie, L., … & Taylor, R. (2018). Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial. The Lancet, 391(10120), 541-551. [accessed June 2022 via: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)33102-1/fulltext#seccestitle10]
14. Lean, M. E., Leslie, W. S., Barnes, A. C., Brosnahan, N., Thom, G., McCombie, L., … & Taylor, R. (2019). Durability of a primary care-led weight-management intervention for remission of type 2 diabetes: 2-year results of the DiRECT open-label, cluster-randomised trial. The lancet Diabetes & endocrinology, 7(5), 344-355. [accessed June 2022 via: https://pubmed.ncbi.nlm.nih.gov/30852132/]
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19. Soares, F. L. P., Ramos, M. H., Gramelisch, M., de Paula Pego Silva, R., da Silva Batista, J., Cattafesta, M., & Salaroli, L. B. (2021). Intuitive eating is associated with glycemic control in type 2 diabetes. Eating and Weight Disorders-Studies on Anorexia, Bulimia and Obesity, 26(2), 599-608. [accessed June 2022 via: https://pubmed.ncbi.nlm.nih.gov/32232778/]
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Nutrition for type 2 diabetes was last modified: June 13th, 2022 by Maeve Hanan