Conventional wisdom tells us that reducing sugar is the best thing you can do to combat prediabetes, so that was the first (and only) thing I did when I got my diagnosis.
I was ruthless and so disciplined. I read nutrition labels for sugar content and made sure I stayed below my daily limit of free sugar for six months.
I was expecting big things at my next blood test, but I would be disappointed. My A1C went from 6.5 to 6.4. Not exactly the kind of dramatic result I was hoping for.
My mistake was believing that reducing sugar would be enough. I did not yet understand the importance of considering total carbohydrates (starch, fibre, and sugars), nor the role of protein in helping control blood sugar.
Making the right choices in carbohydrates, fibre, and protein at each meal and snack ensures a slower release of sugar into the bloodstream. In this post, I’ll look at what all of that means.
The Takeaway
- Carbohydrates break down into glucose and will elevate your blood sugar levels. Choosing healthier carbohydrates, i.e. those higher in fibre and other nutrients, is always advised but even they will raise your blood sugar.
- Pay attention to serving sizes. Carbohydrate servings are smaller than you think so having a visual of what constitutes a serving will help you plan more balanced meals and snacks.
- Distribute your carbohydrate consumption across all of your meals and snacks to keep blood sugar stable throughout the day and avoid sudden spikes.
- Include fibre and protein each time you eat carbs to slow down the release of sugar. Health Canada recommends that carbohydrates be about one-quarter of your meal, protein another quarter and non-starchy fruits or vegetables the remaining half of your dinner plate.
Fibre & Blood Sugar
Dietary fibre is important for managing many health conditions, including high blood sugar and high cholesterol. Most people – prediabetic or not – do not get enough. Here is a brief summary of what fibre is and how it affects blood sugar.
Fibre is the “structural portion” of foods that the body cannot digest. (Joslin Diabetes Center) Fibre is a carbohydrate but because it passes through your body, it does not increase blood sugar. It can, however, help decrease blood sugar. To understand how, we need to look at the two different types:
- Soluble fibre dissolves in water and forms a gel that slows digestion which, in turn, reduces spikes in blood sugar. (This gel also helps lower cholesterol.) It comes from foods like oats, legumes, and many fruits and vegetables.
- Insoluble fibre does not dissolve but it keeps your digestive tract in good working order. (Joslin Diabetes Center). It includes wheat bran, nuts, and leafy greens.
Many foods contain both soluble and insoluble fibre. Both types can play a role in controlling blood sugar but research has shown that soluble fibre has more of an impact on blood sugar levels — it ferments in the gut where it “increases microbiota diversity and SCFA [short-chain fatty acid production]” and “improves “insulin secretion and HbA1C levels.” (Journal of Functional Foods)
Check with your dietitian about your own fibre needs, but Health Canada recommends 25 g of fibre per day for women and 38 g per day for men.
Protein & Blood Sugar
Protein provides your body with amino acids that help “create and repair muscles, tissues, bones, hormones and enzymes.” (Source: Diabetes Australia.)
The role of protein in maintaining muscle mass is particularly important for prediabetics, as muscle uses up a lot of the sugar from the foods we consume, meaning less gets into the blood stream. But protein helps in other ways:
- When eaten with carbohydrates, protein can slow the digestion and rate of release of sugar into the blood. (Diabetes Canada)
- Protein can also increase satiety, meaning you feel full longer and are less tempted to snack on foods that might raise your blood sugar. (Diabetes Australia)
- Many foods that are high in protein are also low in glucose and do not cause the blood sugar spikes that many carbohydrates do. (Joslin Diabetes Center)
For all of these reasons, dietitians recommend including protein in meals and snacks, both to increase your daily totals and to help control the release of glucose and better regulate your blood sugar.
As for the amount, Diabetes Canada recommends daily intake of 0.8 g of protein per kg of body weight for adults. (For those who take their weight in pounds, you can convert to kilograms by multiplying your weight in pounds by 2.2.)
If you are exercising to help manage prediabetes, it is even more important to be aware of your protein needs, since protein is essential to repairing and building the muscles you are working. You may need more than the recommended daily amount. Check with your doctor or a dietitian to confirm the daily amount of protein you need.
Carbohydrates & Blood Sugar
Carbohydrates (carbs) are vital nutrients that include sugars, starch, and fibre. They give us mental and physical energy but they also raise blood sugar, almost as soon as you eat them.
If you are prediabetic, you might be wondering how to balance it all – consuming enough carbs to meet your nutritional needs while avoiding the blood sugar spikes that increase your A1C.
The keys? Being choosy about which carbs you eat and careful about serving size. As noted above, it helps to combine carbs with protein to minimize the impact of the sugars and starches in your meal or snack. It’s also important to distribute your carbs across multiple meals and snacks to keep your blood sugar at a steady level.
TIP: My dietitian told me that sometimes a particular meal or snack, eaten regularly, can cause the type of blood sugar spikes that elevate your A1C. For me it was lunch, when I tended to overeat bread or other starches and not have enough fibre and protein. If you can level out the spikes by adjusting the carbohydrate load of each meal and snack, it might help lower your A1C.
I’ll be honest: making these dietary changes is not easy, at least at first. It took me a very long time to put all the pieces together. I got better on sugar and fibre at first, then protein, but ultimately realized I wasn’t doing a great job of managing my carbohydrate load. I did more research and found what I was missing: an understanding of the ways different types of carbs affect blood sugar, what a serving size looks like, and how to read the carbohydrates section on a nutrition label.
All Carbs Are Not Created Equal: The Glycemic Index
You may have heard of the glycemic index. It is a scale that indicates which foods increase blood sugar the fastest. Whole grains, which tend to include lots of fibre, are considered low-glycemic (GI) foods while foods like white bread are considered high GI.
While it is not always possible (or desirable) to avoid high GI foods, you should aim for the lower side of the glycemic index as much as you can. For example, instead of choosing a banana for a snack, have an apple. Or, if you are having something with a higher GI, combine it with some protein – nuts with a serving of pretzels, or a serving of cheese or hummus with crackers.
For reference, check this Glycemic Index Guide from Diabetes Canada.
Once you get a handle on which carbohydrates to focus on, you then need to consider serving size. Even low GI carbs will raise blood sugar if eaten in excess, so it’s important to know exactly what a serving looks like.
Serving Size
Serving size is critical for moderating carb consumption.
A single serving of carbs is 15 grams (g).
Diabetes Canada recommends 45–60 grams (g) of carbohydrate at meals and 15–30 g for snacks. (My dietitian went a little lower, suggesting 30–45 g at each meal and 15 g at each snack.) Distributing carbs in this way helps keep blood sugar levels stable throughout the day.
NOTE: It’s important to speak with a dietitian about the amount of carbs you should be consuming each day because it can vary based on total daily calories, exercise levels, and whether you are taking any medication to control blood sugar. The recommended minimum seems to land around 130 g. The average diet comes in around 250 g per day which, according to The Johns Hopkins University, is too high for diabetics. There is a lot of variation in recommendations and your healthcare provider will know best what works for you. Carbohydrates provide a lot of energy; you do not want to go too low on this number.
If you are aiming for 45 g of carbs at a meal, you can have 3 single servings of carbs. But what does that look like?
Portion sizes are very distorted in our culture and hard to gauge. For example, you might think your breakfast bagel constitutes a single serving of carbs, but it could be as much as 4 servings, or possibly more, depending on its size.
You read that right: a single carb serving of bread is just one slice or ¼ of a bagel (28.5 g or 1 oz); for rice or pasta, a single carb serving is about 80 mL (⅓ cup).
As you can see from these amounts, it doesn’t take much to meet your carb requirements for a single meal.
When you are first adjusting to the reality of serving sizes, it can help to measure your carbs. Eventually you’ll develop a good enough sense of serving size to eyeball it, but until then, you’ll need your measuring cups and a kitchen scale. Trust me – you need to see these serving sizes to believe them and adapt to them. A visual representation might also help, like this portion guide from Diabetes Canada.
TIP: You don’t have to be obsessive about serving sizes but you should be in the ballpark. It is extremely easy to underestimate size and overeat carbs.
It is also essential to read nutrition labels for the volume of carbs in a single serving of any packaged foods you eat. Knowing you need 30 – 45 g of carbs at a meal is one thing; recognizing the amount of food it takes to reach that level is another.
Nutrition Labels
Nutrition labels tell you the serving size of a given food and the amount of carbs in that portion.
In Canada, the carbohydrates section of a label includes the total carbs along with the amount of fibre and sugar.
This Nutrition Facts document from Health Canada gives a good outline of the current nutrition label. One of its big tips? Subtract the amount of fibre from the total carbohydrate amount to get the net carbohydrate value. As we saw above, fibre does not raise blood sugar so it does not count toward your carb total.
Here is an example of how you can use the nutrition label information with recommended mealtime carb content to arrive at your total carbohydrate load.
The nutrition label below is from a cereal I used to consume as a snack until I realized the carb content is on par with a meal. (Actually, it would be more than a meal since I would often eat far more than the serving size indicated here. This just goes to show how easy it is to overeat carbs.)
For a 23-biscuit (55 g) serving, the carbohydrates are 46 g, minus fibre of 6 g, for a total of 40 g.
So, of 55 g in a serving, which is not a lot, 40 g are counted as carbohydrates. Even if I have this cereal with soy milk, which adds some protein, the carb load is very high.
This is not to say I cannot eat this cereal, but that I have to be aware of the serving size to avoid causing a major blood sugar spike.
Learn More
To learn more about increasing the amount fibre and protein in your prediabetes diet, see Tips for Increasing Fibre and Protein. And even if you bump up both of those things, you will still need to assess your sugar levels and make cuts where necessary. Read Reducing Sugar for ideas on where to look for excess free sugar in your diet.
To read this entire series, visit the Prediabetes Series page.
Disclaimer: I am not a dietitian but have worked with one to learn all I can about prediabetes. I have also done a lot of my own research, from valid sources like Diabetes Canada and books and news articles written by dietitians and doctors. I am speaking here of my own experience and nothing I say should be taken as a substitute for advice from a medical professional. Always consult with a doctor or dietitian before making any lifestyle changes for prediabetes or any other condition.
Photo of kitchen scale by Mathias Reding on Unsplash.