When diagnosed with diabetes, prediabetes, or any form of insulin resistance, the first thing on most people's minds is, "what should I eat?"
Blood glucose comes down to two factors; what you put in your mouth and how your body handles it. Therefore, the perfect diabetes diet should consider how food impacts your blood sugar short-term and how your body responds long-term.
There are a lot of opinions out there as to which diet will produce optimal results, but time and again, it seems as though low-carb eating takes the cake (no pun intended).
In this article, we'll review several studies comparing low carbohydrate and very low carbohydrate diets to several other dietary approaches and pull it all together to determine which eating style is optimal for long-term quality of life and overall health.
Low-Carb Vs. Standard Diet For Diabetes: What The Research Says
#1 Low-Calorie Diet Vs. Low-Carb
Obesity is one of the most common risk factors for type 2 diabetes, and studies show that losing weight can help to re-sensitize your cells to insulin. Among the many weight loss diet approaches out there, calorie restriction is probably one of the most popular.
This is one of the reasons that people with diabetes are often instructed to follow a low-calorie diet – but can it beat out a low-carb diet?
In a 24-week study, researchers assessed the beneficial impact of a low-calorie diet compared to a low-carb diet. They divided a group of over 300 volunteers into two cohorts; one receiving a low-calorie diet and the other receiving a low-carb diet without calorie restriction.
Not surprisingly, at the end of the six months, the investigators found that both groups lost significant weight. Similarly, both groups saw a positive shift in lipid profile.
However, the shift in blood lipids was much more significant for the low-carb group than it was for the low-calorie group. Specifically, the low-carb group saw:
- A significant decrease in triglycerides, total cholesterol, and LDL cholesterol
- Significant increase in HDL cholesterol (the good kind)
While this is impressive on its own, the real kicker was the impact of the diets on blood glucose regulation. Compared with the low-calorie group, the low-carb diet was much more effective at reducing blood glucose levels and HbA1c levels, which measures your body's ability to handle glucose over a 3-month period.
All in all, the study authors concluded that a low-carb diet produces significantly better outcomes for diabetes markers than a low-calorie diet.
#2 Low-Carb Diet W/o Calorie Restriction Vs. Low GI Diet W/ Calorie Restriction
Many people confuse low-carb with low-glycemic. While both types of foods have a reduced impact on your blood sugar, low-glycemic foods aren't necessarily low-carb.
The glycemic index of a food is assessed by comparing the rate at which it increases your blood sugar compared to pure glucose. The slower food is digested and absorbed, the lower the blood glucose spike will be and, therefore, the lower the food's glycemic index (GI).
Some factors that make a food low-glycemic include the food matrix (how much fiber, protein, carbs, and fat there is), the type of carbohydrate (starch vs. simple sugars), and whether the food is refined or whole.
The low glucose impact of these diets makes them another popular choice for people with diabetes. But can low GI beat out low-carb?
In a study with 84 volunteers with obesity and type 2 diabetes, investigators divided the participants into a low-carb ketogenic diet group and a low-glycemic group. To give the low-GI group a little edge, they also reduced their daily calorie intake by 500 calories per day, while the low-carb group received no instruction on calorie reduction.
The study lasted for six months, and during that time, both groups received nutrition supplementation, exercise recommendations, and participated in group meetings.
At the end of the study, both groups saw improvements in hemoglobin A1c, fasting glucose, fasting insulin, and they both experienced weight loss.
However, the keto diet group saw more significant improvements in weight loss and hemoglobin A1c and displayed higher HDL levels.
Furthermore, 95% of the participants in the low-carb group were able to reduce or eliminate diabetes medications, while only 62% were able to do so in the low-GI group.
The takeaway; although both groups saw improvements, the low-carb group was able to shed more pounds (despite the lack of calorie restriction) and display more significant shifts in diabetes markers to the point where nearly the entire cohort could reduce or eliminate medication.
#3 Low-Carb Vs. Normal Carb Diet
While reducing carbohydrates has obvious benefits for diabetes (the fewer the carbs, the lower the blood glucose), some diabetes educators will instruct a diet that contains what would be considered a "standard" amount of carbs. Technically, a "normal carb" diet would range from about 55-60% of total calories per day coming from carbohydrates.
How does the standard carb diet hold up against low-carb?
In a retrospective study, investigators followed up on a 6-month trial to assess how the participants were getting on after 22 months post-intervention on either a low-carbohydrate or high-carbohydrate diet and then again after 44 months.
In the study, the researchers were looking for markers of cardiovascular health and diabetes.
During the initial six-month trial, participants with obesity and diabetes were instructed to follow either a low-carb diet (20% of calories coming from carbs) or a standard carb diet (55-60% of calories coming from carbs). At the end of the six months, the low-carb group saw significant improvements in body weight and HBa1c when compared to the higher-carb group.
At the 22-month follow-up, the participants in the low-carb group that stuck to the diet maintained those gains, and at the 44-month follow-up, all but one participant in the low-carb group displayed lower body weight than they did at the beginning of the trial.
Furthermore, of the participants that were in the low-carb group, only 8% suffered a cardiovascular event during the 44-month follow-up, while 66% of people in the higher-carb group had suffered at least one cardiovascular event.
This reveals that the low-carb diet not only provided stable body weight and blood glucose control but also significantly reduced the risk for cardiovascular events.
#4 Low-Fat Reduced Calorie Diet Vs. Low-Carb
In addition to calorie restriction, low-fat dieting has been a go-to for many decades (although research continues to show that this may not be the best way to shed pounds after all).
If you have a pretty good understanding of biology, a low-fat diet may seem a bit counterintuitive for diabetes since fat has a very low impact on blood glucose – nonetheless, some health professionals still recommend it as a weight loss protocol.
In a six-month study, researchers divided a group of severely overweight individuals who either had diabetes or were at high risk into two cohorts; low-carb (no calorie restriction) or low-fat with calorie restriction. Again, the low-fat group had the added edge of calorie restriction, whereas the low-carb group was given no calorie intake guidelines.
At the end of the trial, the low-carb group lost three times the amount of weight as the low-fat group, and fasting blood glucose was reduced by 26% in the low-carb group, whereas the low-fat group only saw a 5% blood glucose reduction.
Furthermore, despite the higher fat content of their diet, the low-carb group saw greater improvement in blood triglycerides than the low-fat calorie-restricted group.
What does this tell us? Low-fat dieting may work for some people, but if you have diabetes, your best bet is to keep healthy fats in your diet while reducing your carbohydrate intake.
Low-Carb Dieting And Long-Term Quality Of Life
For diabetics, it's not only the risk of blood sugar irregularities and insulin spikes that can lower quality of life but also all of the compilations that can come along with dysregulated glucose. When blood sugar levels remain high for too long, it can damage other organ systems in your body.
For example, having a diabetes diagnosis also increases the risk of:
- Retinopathy (the most common cause of blindness in adults)
- Neuropathy (nerve damage)
- Nephropathy (damage to the kidneys)
- High blood pressure
- heart disease (stroke and heart attack)
With that being said, once glucose is under control, the risk for these conditions greatly reduces as your body is no longer under the assault of high blood sugar.
While the studies in this article show that each type of diet can lead to some improvements in diabetes outcomes, the low-carb diet is by far the best at controlling blood sugar and lowering HbA1c. It also stands far above the rest when it comes to weight loss and cardiovascular markers.
When viewing this data from a long-term quality of life lens, it's clear that choosing a low-carbohydrate diet will likely produce the most optimal outcomes in the majority of people with diabetes.
It also paints a hopeful picture for people with a diabetes diagnosis that their body has the ability to bounce back, and a diagnosis is not a determinant of destiny.
While diabetes management comes down to several factors, the diet you choose to follow plays a significant role.
Carbohydrate restriction can look different for everyone, but across the board, it appears that watching the amount of carbohydrates you consume can produce outcomes that are beneficial not only for diabetes but also for other comorbidities like heart disease.
In the past, calorie restriction and low-fat diets were the go-to for weight loss and metabolic management, but research shows that an eating plan that includes healthy, high-fat foods like olive oil, avocados, and coconut oil produces more significant and long-lasting results.
A lot of people struggle when starting off on a low-carb diet, which is why BioCoach offers guidance for meal planning, carb intake, and macronutrients, among other tips and tricks for those new to keto or low-carb.
Check out the BioCoach website to learn more, and see if the low-carb lifestyle is right for you.
- Hussain, Talib A., et al. "Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes." Nutrition 28.10 (2012): 1016-1021.
- Westman, Eric C., et al. "The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus." Nutrition & metabolism 5.1 (2008): 1-9.
- Nielsen, Jörgen V., and Eva A. Joensson. "Low-carbohydrate diet in type 2 diabetes: stable improvement of bodyweight and glycemic control during 44 months follow-up." Nutrition & metabolism 5.1 (2008): 1-6.
- Samaha, Frederick F., et al. "A low-carbohydrate as compared with a low-fat diet in severe obesity." New England Journal of Medicine 348.21 (2003): 2074-2081.
- Dashti, Hussain M., Thazhumpal C. Mathew, and Naji S. Al-Zaid. "Efficacy of low-carbohydrate ketogenic diet in the treatment of type 2 diabetes." Medical Principles and Practice 30.3 (2021): 223-235.