Diabetes and Carbohydrate: Clearing Up Carb Confusion

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Diabetes and Carbohydrate: Clearing Up Carb Confusion

Everyone has an opinion about carbohydrate these days, it seems. Those who are devoted to low-carb and keto diets are firm in their convictions and are often more than eager to spread the word of their success with these diets. And there are those who support the inclusion of carb foods in one’s eating plan, with a focus on choosing “healthy” carbs.

When it comes to diabetes, scientific evidence supports different ways of eating. The American Diabetes Association calls these “eating patterns,” and these encompass an array of options, such as Mediterranean, vegetarian/vegan, low fat and yes, even low carb. The bottom line is that there is no one “right” way for a person with diabetes to eat, given that person’s food preferences, cultural background, health conditions and financial circumstances.


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Whether you’ve chosen to go the low-carb route or to incorporate carb foods in your eating plan, making sense of carbs can sometimes be tricky. Are all carbs the same when it comes to blood sugar management? How do you choose “healthy” carbs for you and your family? Let’s see if we can cut through some of this carb confusion.

Diabetes and carbohydrate: Carbohydrate 101

Carbohydrates (“carbs”) are sugars, starches and fiber that occur naturally in food. These three types of carbs have one thing in common: they’re all made up of sugar molecules. Carbs are often classified into two main categories:

Simple carbohydrates

These include sugar that is naturally found in fruits, vegetables and milk, as well as white and brown sugar, honey, molasses and sugar added to foods during processing (think candy and soda). Simple carbs tend to raise blood sugar levels quickly, which is why they’re recommended when your blood sugar goes too low.

Complex carbohydrates

These include starches and fiber and consist of longer chains of sugar molecules. They take longer to digest than simple carbs. Examples of complex carbs include potatoes, bread, beans, corn and cereal. Because complex carbs break down more slowly, they may not have as quick of an impact on glucose levels as simple carbs. Also, fiber isn’t fully digested and has a minimal effect (if any) effect on blood glucose.

The main purpose of carbohydrate is to fuel the body. Carbs are a more readily available source of energy for the body; glucose from carb is quickly converted to energy by muscle and brain cells. Protein and fat provide energy, as well, but certain cells and tissues in the body require glucose as their source of fuel, including brain cells (neurons), red blood cells and tissues in the eyes. Also, protein’s primary role is to help build cells and muscles, not to provide energy.

Refined vs. unrefined carbs

If you’re looking to fit healthier carb foods into your eating plan, it helps to understand the difference between refined and unrefined carbs.

Refined carbs

These are carbs that have been altered (refined) during manufacturing. When it comes to refined grain foods, for example, the bran and the germ (the most nutritious parts) from the grain are stripped away, leaving just the starch. White flour (and products made from white flour, such as white bread) and white rice are examples of refined grains. High-fructose corn syrup is an example of a refined sweetener; it’s made from corn syrup. Table sugar is another refined sugar that is manufactured from sugar cane or sugar beets.

Unrefined carbs

These are carbs are generally considered to be “good” carbs because they are rich in vitamins, minerals, phytonutrients and fiber. Nothing has been stripped away, in other words. Examples of unrefined carbs include whole-wheat bread, brown rice, oatmeal, whole fruit, lentils and peas.

Healthwise, refined carbs have little to offer other than calories, and they rank low in terms of nutritional value. Studies link the consumption of refined carbs with diseases such as type 2 diabetes, heart disease, obesity and cancer. Diabetes-wise, refined carbs tend to be digested more quickly than unrefined carbs, leading to spikes in glucose levels. Blood sugar spikes can leave you feeling drained, irritable and hungry.

Unrefined carbs provide a variety of essential nutrients and help to support whole body health. In addition to providing energy to the body, these healthy carbs can lower the risk of heart disease, obesity, and certain types of cancer, including breast, colorectal and prostate cancer. When it comes to blood sugar management, unrefined carbs are digested more slowly and therefore less likely to cause those blood sugar spikes that you work so hard to avoid. They also have the added benefit of help you feel full and stay full for longer periods of time.

Processed and ultra-processed carbs

Another term that you might be familiar in regard to carbohydrate is “processed.” “Processed foods,” according to the Academy of Nutrition and Dietetics, “includes food that has been cooked, canned, frozen, packaged or changed in nutritional composition with fortifying, preserving or preparing in different ways.” It might surprise you to realize that anytime you cook, bake or prepare your foods you are processing them.

In this sense, processed foods don’t seem so bad. But processed foods have a dark side, especially when less-than-healthful ingredients, such as sugar, salt, fat and certain food additives are added to foods. This is where ultra-processed foods come in.

According to the Harvard Health Blog, ultra-processed foods “most likely have many added ingredients, such as sugar, salt, fat and artificial colors or preservatives.” Examples include hot dogs, cold cuts, frozen meals, soft drinks, cookies, salty snacks and fast foods.

To better understand the concept of processed foods, here are a few examples of how a food can go from being minimally processed to processed to ultra-processed:

· Carrot > carrot juice > carrot cake

· Potato > baked potato > potato chips

· Apple > apple juice > apple pie

Again, a “processed” food doesn’t necessarily mean an unhealthy food (a baked potato is processed because it’s baked, but baking doesn’t turn a raw potato into an unhealthy potato). Ultra-processed foods are the foods to limit. They tend to be sources of empty calories with added sugar and unhealthy fats. Not surprisingly, these foods don’t do much for our health, either. In fact, research points to a diet high in ultra-processed foods increasing the risk of diabetes, heart disease, high blood pressure, obesity and certain cancers.

And some ultra-processed foods, such as soda and candy, are more likely to raise blood glucose levels compared with unrefined foods. Not sure if a food is ultra-processed or not? Check the ingredient list. If you see more than two or three ingredients, plus a long list of hard-to-pronounce names, there’s a good chance that it’s ultra-processed.

Fast carbs vs. slow carbs

Here’s yet another way to view carbs: as either “fast” or “slow.” Fast and slow carbs aren’t that difficult to figure out, at least when it comes to managing diabetes. In fact, if you take insulin or certain types of diabetes pills, such as sulfonylureas, you are probably already familiar with the concept of fast carbs.

Fast carbs

Fast carbs are digested quickly and released quickly into the bloodstream as glucose. The main result of these carbs is to raise blood sugar levels fast. You want your blood sugar to come up quickly when it’s too low (the definition of low blood sugar, or hypoglycemia, is a blood sugar of below 70 mg/dl). But when it’s not low, you don’t need carbs giving your glucose a boost.

In many instances, fast carbs have a high glycemic index (GI), which is a ranking of a carb food’s impact on glucose levels. The higher the GI, the more likely that food will rapidly increase glucose. A food with a GI of 70 or higher qualifies as a fast carb.

Simple carbs, such as sugar and honey are fast carbs, as are many types of candy, like gumdrops and jellybeans. But other refined carbs are fast carbs, too: white bread, pretzels, instant mashed potatoes and cornflakes fall into this category.

Slow carbs

Slow carbs, on the other hand, take longer to digest and lead to a slower rise in blood sugar. They’re less likely to cause a spike in your blood sugar, in other words. They’re also more likely to have a lower GI. What foods are slow carbs? Here are some examples:

· Whole-wheat bread

· Brown rice

· Lentils

· Chickpeas

· Berries

· Apples

· Sweet potatoes

· Spinach

· Broccoli

· Tomatoes

· Onions

Once you get the hang of it, it’s easy to differentiate between fast and slow carbs. As Rosemary Takacs, RN, CDCES, and director of diabetes education, cardiovascular risk and weight management at The Wright Center for Community Health in Scranton, PA, puts it, “I compare a fast carb like OJ and how it impacts blood glucose, then show how a slow carb with fiber raises blood glucose so much slower.”

Smart carb eating

The concept of “slow carb eating” has taken hold and has even pushed the idea of low- or no-carb eating aside to some degree. Drastically cutting back on carbs altogether can be difficult for many people, especially over the long-term. Cutting out groups of food can leave you feeling deprived, and can also shortchange you on important nutrients, such as fiber, many vitamins and minerals, and antioxidants. Plus, studies show that including whole grains and fiber in your diet can help you maintain a healthy weight and cholesterol level, and even help you live longer.

If you’re doing well with lower-carb eating and feel that it’s sustainable for you, great! But if you’re struggling to manage your blood sugars and can’t seem to stick with a lower-carb plan, maybe a smart carb way of eating is better suited to you. Here are some tips to get you going:

· Consider meeting with a dietitian to discuss your carb goals for meals and snacks.

· Identify your current sources of carb and think about healthier alternatives (e.g., switch out those cornflakes with steel-cut oats, or white rice with quinoa).

· Keep an eye on carb portions. Carbs do impact blood sugar, after all, so don’t go overboard. Knowing your carb goals can help you with portion control.

· Aim to fill half of your plate with low-carb veggies (green beans, broccoli, asparagus, tomatoes, etc.). You can pretty much eat your fill of these foods, as they are very low in carb and good sources of fiber.

· Keep tabs on your blood sugars! Anytime you make changes to your diabetes treatment plan, check your blood sugars more often. For example, consider checking before and then two hours after a meal to learn how your food choice impact your glucose levels.

To learn more about fast and slow carbs, check out the book “Fast Carbs, Slow Carbs: The Simple Truth About Food, Weight and Disease.” And to get you on your way to smart-carb eating, give this tasty soup recipe a try

Want to learn more about carbohydrate and diabetes? Read “Counting Carbohydrates Like a Pro” “Keto Diet for Diabetes: Help or Hindrance?” and “Low-Carb Myths and Facts.”

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES on social media

A Registered Dietitian and Certified Diabetes Educator at Good Measures, LLC, where she is a CDE manager for a virtual diabetes program. Campbell is the author of Staying Healthy with Diabetes: Nutrition & Meal Planning, a co-author of 16 Myths of a Diabetic Diet, and has written for  publications including Diabetes Self-Management, Diabetes Spectrum, Clinical Diabetes, the Diabetes Research & Wellness Foundation’s newsletter,, and

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