Eat to Thrive Podcast #10: Nutrition and Diabetes
November is Diabetes Action Month, so it's a good time to take a look at how some important tweaks to your nutrition can help manage this common condition.
There are more than 240,000 people in New Zealand living with diabetes. It is estimated that another 100,000 people have diabetes but don't know it. The theme of Diabetes Action Month this year is to encourage anyone who is experiencing symptoms that may indicate they have diabetes, or those at greater risk of diabetes, to get tested. Early diagnosis and management is crucial in avoiding some of the serious complications that can come from chronically elevated blood glucose levels.
So I suppose it would be a good idea to start with some definitions...
When we talk about diabetes, what do we mean?
The general overview of diabetes is that it’s when the body can’t properly regulate the level of glucose in the blood, and it stays higher than it should. Now we need glucose in our blood because our cells use it to produce energy, which allows our body to do all the things it needs to do. I’m not just talking about doing exercise - going for a walk or a run, playing sport, that kind of thing; our body requires energy to exist – we burn energy just being alive. We could lie in bed all day and do absolutely nothing, and still require a lot of energy keep our organs working, and keep all the processes in our body running. Most of the glucose we need comes from the digestion of the carbohydrates in our food, but the body is pretty clever at making sure we can still function when it can’t get its hands on any carbs for whatever reason. We store glucose in our liver, and glucose can also be made from some amino acids from protein, and from a small part of certain fat molecules. But the main source of the glucose we need is the carbs in our diet.
An organ called the pancreas produces the hormone insulin, and insulin acts like a key in the door to the cell, letting glucose into the cell to be used to produce energy. If we develop diabetes, either our body doesn’t produce enough - or in some cases any -insulin (insulin deficiency), or our cells don’t respond as they should to the insulin we produce (insulin resistance). Effectively, either we don’t have a key to the door, or the door doesn’t recognise the key.
So that’s the general picture, but there are different types of diabetes, with some important distinctions, and we’ll start with:
Type 1 diabetes:
This used to be called early onset or juvenile diabetes, but it can also develop during adulthood. It’s an auto-immune condition, which means the body’s immune system goes a bit haywire and starts attacking the cells in the pancreas that make insulin, destroying them. This means you can’t make the key to open the door to the cells and let glucose in, and your blood glucose levels stay high. This damage to the pancreas can occur in a very short period of time, and it’s a life-threatening situation – a medical emergency. Thankfully, there is excellent support for those newly diagnosed with Type 1 diabetes, as managing the condition is a steep learning curve with pretty serious consequences if you get it wrong, all while you’re coming to terms with what is a life-altering diagnosis. You will be reliant on insulin injections for the rest of your life, and you will need to know exactly how much carbohydrate you are eating at each meal, to know how much insulin to inject. Around 10% of all cases of diabetes are Type 1, and there is a strong genetic component – if you have a close blood relative with Type 1, you are at a greater risk of developing it yourself. Type 1 can’t be prevented, only managed.
Then we have Type 2 diabetes:
This develops over a longer period of time, and for most people is related to lifestyle behaviours – mainly nutrition and physical activity – but for some there is a genetic link. Type 2 usually develops in adulthood, although there are an increasing number of teenagers and children being diagnosed. It starts with insulin resistance – the door doesn’t recognise the key – and our pancreas responds by producing even more insulin to unlock those cell doors. Kind of a battering ram to get the door open really. If you don’t take steps to manage your blood glucose levels, over time this extra insulin production may lead to exhaustion of those special cells in the pancreas, and that’s when you will stop producing any insulin at all. Type 2 diabetes accounts for around 90% of all cases of diabetes, and it’s estimated around 80% of cases of Type 2 can be prevented through lifestyle changes.
There is also another type of diabetes called gestational diabetes:
As the name suggests, this develops during pregnancy, and is a temporary condition, usually disappearing after the birth of your baby. You will need to be closely monitored by your Lead Maternity Carer and your GP, to ensure your blood glucose is well managed during the remainder of your pregnancy, to minimise the risk to your baby.
Signs and symptoms to look out for
There are some important indicators to keep your eye out for, and should you be experiencing any of the following, it's time to head to your General Practitioner (GP) for a check-up:
Needing to pee frequently
Being really tired all the time
Your vision may get a little blurred
Wounds that take ages to heal
Tingling or numbness, especially in your feet
How is diabetes diagnosed?
Your GP will take some blood and check something called your glycated haemoglobin – or HbA1c level. This is a measure of how much glucose is stuck to the haemoglobin in your red blood cells, and an indication of your blood glucose levels over the previous 3 months.
So, what are the health implications of diabetes?
Aside from those with Type 1 diabetes, or insulin-dependant Type 2, who are at risk of coma and death if their blood glucose levels are allowed to get too far out of control, the impact on your health comes mostly from chronically elevated blood glucose levels.
If your blood glucose remains high – also called hyperglycaemia – this causes damage to the blood vessels in your body. Damage to the major blood vessels (arteries and veins) can double or triple your risk of cardiovascular disease , while damage to the tiny blood vessels (capillaries) increases your risk of kidney failure, loss of eyesight, nerve damage, and loss of circulation, especially in your feet. Such damage can require the amputation of feet and legs.
Your body may also find fighting infections is harder, due to the increased glucose levels in your blood and urine providing a ready food supply for bacterial growth.
So, what do I do if I am diagnosed with diabetes?
This will vary a little depending on the form of diabetes you have been diagnosed with. If it’s Type 1, you will need to manage your condition with a combination of insulin injections and lifestyle changes as directed by your GP or specialist. If it’s Type 2 but your pancreas is still producing insulin, you will manage your diabetes with a combination of prescribed medication from your GP and lifestyle changes. If your Type 2 has progressed to the point that your pancreas is no longer producing insulin, then the management will be the same as for Type 1 – insulin injections and lifestyle changes.
The one common theme you may have spotted in the in these management strategies is the mention of “lifestyle changes”.
What do you mean by “lifestyle changes”?
Nutrition and physical activity.
These two strategies work on two main avenues of diabetes management:
Moderating your blood glucose response to the food you eat (so you don’t have big spikes in blood glucose after meals), and
Reducing how resistant you are to the action of insulin (getting the door open with less insulin required to do it)
Regular physical activity increases your cells sensitivity to insulin
In other words, exercising can decrease your resistance to the action of insulin. This means that your pancreas won’t have to work as hard and produce more insulin to open the door in the cell to let in the glucose. If you have Type 1, or insulin-dependant Type 2, you won’t need to inject quite as much insulin to get the door open. These improvements to insulin sensitivity are seen even in the absence of any weight loss, emphasising the benefits of focussing on lifestyle changes rather than weight loss. There are some comprehensive guidelines on introducing physical activity into your regular routine on the Diabetes New Zealand website, for both those with Type 1 and Type 2, but before you start anything new, see your GP to get their advice on what’s appropriate and safe for you.
OK, so that’s the physical activity part, what about the nutrition part? Do I have to eat a special diabetes diet, and diabetic foods?
Good question! Now we’ll take a dive into the dietary changes you can make to better manage your diabetes. The great news is there is no special diabetes diet – just very similar guidelines to the ones that people without diabetes should be following!
Each day, aim for:
3-4 serves of non-starchy vegetables: the more variety and colour during the day the better. These vegetables contain very little carbohydrate, so they have minimal effect on your blood glucose.
3-4 serves of fruit: spread throughout the day, avoiding tinned fruit in syrup.
2-3 serves of dairy: choosing reduced-fat and unsweetened options to minimise the effect on your blood glucose.
1-2 serves of protein foods a day: making sure you cut off any visible fat and use lower-fat cooking methods.
6 serves from the starchy carbs group: this group includes foods like rice, pasta, legumes, potatoes, kumara, breads and cereals. Choosing breads and cereals higher in fibre and preferably wholegrain will slow the digestion of these carbohydrate-rich foods, moderating their effect on your blood glucose levels.
As you can see the guidelines are pretty much the same as healthy eating advice for people without diabetes, and are general enough so you can work within your food preferences. The aim is to select foods that are high in fibre, and low in fat, added sugar and salt, and to avoid quickly-digested carbs that will lead to spikes in your blood glucose levels, making your diabetes easier to manage. For more information, check out the Diabetes New Zealand website, and their excellent pamphlet “Diabetes and healthy food choices” which you can download for free.
The pamphlet also includes a handy visual guide for serving up meals called the Healthy Plate Model:
½ of your plate filled with colourful, non-starchy vegetables
¼ of your plate starchy carbohydrate foods, like rice, potatoes, kumara, or pasta
and the other ¼ of your plate is where the protein foods go: meat, chicken, fish, eggs, nuts, seeds, tofu, that kind of thing.
There’s also lots of additional info on selecting foods within certain food groups, and help with reading food labels. The Diabetes New Zealand website also has a selection of recipes, as well as a recipe book you can purchase and have mailed to you.
Healthy Food Guide have also put together a Diabetes Tool Kit, with some great info (and not surprisingly some delicious recipes!), so head to their website and download the e-book for a very small cost.
There are some suggestions that low-carb diets, and maybe even ketogenic diets (these diets are so low in carbohydrates that the body is forced to burn fat for fuel) should be recommended for the management of diabetes, due to their effects on blood glucose control. However, such diets are necessarily higher in fats (albeit sometimes healthier fats), often high in protein, and low in wholegrains, and there simply is not enough data currently to recommend them as a long-term diabetes management strategy. Some research has shown such diets can increase the levels of “bad” cholesterol in the blood, which isn’t a great outcome if you already have a higher risk of cardiovascular disease;
and the higher level of dietary protein may have an impact on kidney health. A large study in 2018 showed a moderate carbohydrate intake (neither high or low) is associated with living longer, although it very much depended on the quality and source of the carbohydrates: high fibre, wholegrain and plant-based carbs conferred the greatest benefits to longevity.
I would also be concerned about the impact of a low carb diet on gut health, as you would necessarily be consuming very little (if any) wholegrains, and we know they are essential for maintaining a diverse and plentiful population of good gut bugs.
If you are considering trying a low carb or ketogenic diet to manage your diabetes, please seek the advice of a Registered Dietitian – they are qualified to supervise medical nutrition therapy, which is what these types of diets are.
So avoiding all the fad diets, and following the current evidence:
Here are some top tips to help you better manage your diabetes:
Choose breads, wraps, rolls with at least 6 grams of fibre per 100 grams, and preferably wholegrain.
Choose cereals with at least 6 grams of fibre per 100 grams, less than 15 grams of sugar per 100 grams (up to 20 grams if the cereal contains fruit), and less than 10 grams of fat per 100 grams.
Spread your carbohydrate-rich foods throughout the day (fruit, breads, cereals, rice, pasta, potatoes, kumara, legumes).
Limit your intake of: lollies, biscuits, cake, added sugar, fatty foods, sauces and dressings, cheeses, pastries and ice-cream. It doesn’t mean you can never eat them again, just small amounts, and be aware of the effect they will have on your diabetes management. Over time, your taste buds will adjust to a reduced-sugar diet and you will likely find sugary foods far less pleasant to the taste.
Honour your hunger: if you are hungry, eat! Don’t think you need to starve yourself or go on some restrictive diet; just choose foods that will help your diabetes management. In fact, weight cycling, or the repeated loss and gain of weight due to dieting, will make the management of your diabetes much more difficult. Remember, if you do lose weight, you will still have to manage your diabetes by eating a healthy diet.
There are many additional resources to be found on the Diabetes New Zealand website:
Essentials of healthy eating (simplified)
Bird, S.R., & Hawley, J.A. (2017). Update on the effects of physical activity on insulin sensitivity in humans. BMJ Open Sport and Exercise Medicine, 2(1). Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5569266/pdf/bmjsem-2016-000143.pdf Bolla, A.M., Caretto, A., Laurenzi, A., Scavini, M., & Piemonti, L. (2019). Low-Carb and Ketogenic Diets in Type 1 and Type 2 Diabetes. Nutrients, 11(962). Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566854/pdf/nutrients-11-00962.pdf
Diabetes New Zealand. (n.d.). Complications of diabetes. Retrieved November 1, 2019, from: https://www.diabetes.org.nz/complications-of-diabetes
Diabetes New Zealand. (n.d.). Gestational diabetes. Retrieved November 1, 2019, from: https://www.diabetes.org.nz/gestational-diabetes
Diabetes New Zealand. (n.d.). Understand Type 1 diabetes. Retrieved November 1, 2019, from: https://www.diabetes.org.nz/type1diabetes
Diabetes New Zealand. (n.d.). Understanding Type 2 diabetes. Retrieved November 1, 2019, from: https://www.diabetes.org.nz/understand-type-2-diabetes
Health Direct. (2018). HbA1c test. Retrieved November 1, 2019, from: https://www.healthdirect.gov.au/hba1c-test
Health Navigator. (2019). Type 1 diabetes. Retrieved November 1, 2019, from: https://www.healthnavigator.org.nz/health-a-z/d/diabetes-type-1/
Health Navigator. (2019). Type 2 diabetes. Retrieved November 1, 2019, from: https://www.healthnavigator.org.nz/health-a-z/d/diabetes-type-2/
International Diabetes Federation. (n.d.). Care and prevention. Retrieved November 1, 2019, from: https://www.idf.org/our-activities/care-prevention/cardiovascular-disease.html
International Diabetes Federation. (n.d.). What is diabetes. Retrieved November 1, 2019, from: https://www.idf.org/aboutdiabetes/what-is-diabetes.html
Ministry of Health. (2018). Diabetes. Retrieved November 1, 2019, from: https://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/diabetes
Seidelmann, S.B., Claggett, B., Cheng, S., Henglin, M., Shah, A., Steffen, L.M., Folsom, A.R., Rimm, E.B., Willett, W.C., & Solomon, S.D. (2018). Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. Lancet Public Health, September 2018(3). Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6339822/pdf/nihms-989986.pdf