Key Takeaways:
1.) Strength training regularly seems to reduce your risk of getting type 2 diabetes, independent of weight, BMI, or other factors.
2.) Strength training seems to help mitigate symptoms of type 2 diabetes for those who already have it.
3.) Higher intensity strength training likely yields greater benefits in reducing symptoms for those who already have type 2 diabetes, though all intensities of strength training have some effect.
4.) People with diabetes are safe to engage in resistance training, though there is not a clear standard regarding optimal training type and dose.
I have been getting asked a lot of questions lately via TikTok about health and longevity. Specifically, questions about cardio and strength training, and their powers in reducing your risk of getting certain diseases, increasing lifespan, and other things. I wanted to narrow the scope of these questions for today's article, and focus singularly on strength training and its correlation to diabetes prevention and management.
Now, before I start this article, please note: I am not a doctor. I'm not a diabetes, or healthcare professional. I am a personal trainer, and I am giving you my view of the current evidence from perspective of someone who works with people who use exercise to improve their quality of life. I know my bias is obviously in favor of exercise, but I will try and look at the evidence as objectively as possible, then draw conclusions based on a large amount of studies and personal experience, while considering individualization from the clients I have worked with.
If you have any concerns about anything I say here, you should always talk to your doctor or healthcare professional first before engaging in any activity you are unsure of. You may additionally send me your thoughts via email at jonnyreps@gmail.com. Now that that is out of the way, let's go!
Before we talk about how strength training can have an effect on diabetes, I think it would be a good idea to first define both diabetes and strength training...
Diabetes
Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high (1). Chronically having too much glucose in your blood can lead to an increased risk of many different types of diseases. Even in healthy people, blood glucose will naturally rise and fall based on what you eat, when you eat, and a variety of other factors.
This is not bad, and you should not entirely avoid foods that impact blood sugar, especially, if you aren't diabetic yet. Even if you are diabetic, it is very hard to avoid all foods that impact blood sugar, so a better strategy is to educate yourself about these foods, how you can fit them into your diet (11). For those without diabetes, which is the majority of you, blood sugar is probably something you don't need to worry about managing.
However, there is a large portion of the population who DOES have diabetes. Nearly 18% of the US population has diabetes or pre-diabetes (1). If this is you, I recommend looking to the American Diabetes Association for clinical and evidence-based ways in managing your disease (13).
Insulin is a hormone that your body makes, which helps the glucose in your blood get transferred into your cells. Your cells use glucose as energy, and those with diabetes either have insufficient amounts of insulin, their body doesn't make insulin at all, or their body doesn't utilize insulin well (2). There are two main types of diabetes.
Type 1 Diabetes - your body does not make insulin. Type 1 diabetes seems to be mostly genetic and / or environmentally caused, though the exact causes are still somewhat of a mystery (12). There seems to be little definitively known about preventing or curing type 1 diabetes, so those who have it need to take insulin every day or they will, quite literally, die (2). There does seem to be one drug currently in clinical trials that may help delay the development of type 1 diabetes, but it is still in very early trial stages (3). As far as we currently know though, type 1 diabetes has no cure.
Type 2 Diabetes - occurs when your body makes some, but not adequate amounts of insulin, or it does not utilize the insulin it makes very well (2). The concept of "insulin resistance" is when your body's cells become resistant toward using the insulin from your pancreas for its intended purpose. I.e. your pancreas secretes adequate amounts of insulin, but your body does not use it effectively (4).
There are other types of diabetes that are much less common. However, since type 1 diabetes is incurable, and the other types are very rare, this article will focus mainly on type 2 diabetes.
Strength Training
I generally define strength training as "any type of exercise program that is designed with the goal of improving your body's ability to demonstrate strength". We will go a little bit broader because we don't want to have too narrow of a definition that excludes valuable studies that could help inform our opinion on the matter at hand. For the purposes of this article, we will define strength training as, "any type of exercise that uses resistance as a primary component."
What does this include? This would include things like bodyweight training, barbell training, machine training, exercise bands, and other similar protocols. Essentially, anything that includes moving through a range of motion under load.
I would not include studies relating to things such yoga, cardiovascular focused protocols like running and swimming, sports specific protocols (such as playing a sport) and things of this nature. I understand that this is an arbitrary line, but I want to focus mainly on the correlation between strength training and reduction in diabetes risk. Anyway, let's move on.
Some Evidence For Strength Training And Diabetes.
Surprisingly, there exists little epidemiological evidence that shows a direct connection between strength training and reduction in diabetes risk. Epidemiological evidence is evidence that comes from real world conditions. It's one thing to have proposed mechanisms for how things could theoretically work, or even studies showing that they do work in the laboratory conditions. It's a whole different ball game to have actual proof of these things having an impact in the real world (14).
What epidemiological studies do is they usually look at large populations of people and track certain variables over time. They then look for correlations between these variables.
In 2015, one epidemiological study looked at over 26,000 male and female Japanese workers between the ages of 30 and 64 during 5.2 years. Throughout the study period, the evidence showed that those who regularly engaged in strength training saw about a 34% reduction in risk of acquiring type 2 diabetes (5).
Another interesting note: adjusting for BMI did not significantly impact the results. People still had a greatly reduced risk of getting type 2 diabetes, even if they were overweight or obese, simply by engaging in strength training. That means that independent of body weight, strength training seems to have a significant impact in reduction of diabetes risk under real world conditions. At least in this study. What other evidence do we have?
Well we have some evidence looking at strength training and symptoms in those who already have diabetes. I.e. If you already have diabetes, can strength training do anything to help? A 2007 study looked at just that.
They took 62 Hispanic adults over the age of 55. Group one, the control group, engaged in the standard practice of care for diabetes. That means that they are directly comparing strengths training to the best known interventions. These studies are particularly helpful, because they show if the variable they are attempting to study may be more effective than what is currently considered the appropriate medical care in treating that disease (6).
While group 1 received the standard of care, group 2 participated in resistance training in addition to the standard care for type 2 diabetes. They observed the effects of this over a 16 week study period.
As expected, the group that performed strength training showed increased muscle and increased strength. However, they also found that this 16 weeks of strength training reduced insulin sensitivity throughout the entire body (6). Remember how we said at the beginning of the article that insulin sensitivity is one of the key factors in diabetes? Yeah, that's important. If strength training can reduce the body's insulin sensitivity, may it hold the key to curing diabetes?
I think such a simple and one dimensional assessment is simply put, never true. It is obviously far more complex than that. Strength training can't cure diabetes, and anyone claiming that it can is a pure snake oil salesman. But it seems like there is good promise in strength training being helpful for both reduction of risk, and reduction in symptoms of type 2 diabetes.
Larger scale studies
Larger scale works, such as literature reviews, meta-analyzes and systematic reviews look at a large number of studies simultaneously and see if there are common threads between these groups of data. While they may not be as precise in pinpointing specific things in specific populations, they give a larger body of evidence which to draw conclusions from.
A 2019 meta-analysis looked at if intensity of resistance training played a role in reducing type 2 diabetes symptoms. The results showed that while all forms of exercise reduced markers of diabetes (HbA1c, and insulin levels), the higher the intensity of the exercise, the more it reduced these markers.
This means that harder exercise is better in reduction of diabetic symptoms. But the analysis also showed that easier exercise does have a clinically significant effect. It is just not as profound.
There was also an equal reduction in blood glucose levels (blood sugar) shown across all intensities of resistance training. This means that you can reduce your blood sugar by a similar amount with high and low intensity resistance training, even though higher intensity training has a larger effect on other markers and symptoms of diabetes (7).
There's a much other data regarding resistance training and diabetes outcomes. Most tends to trend in this direction. More profound results are seen from higher intensity and larger amounts of strength training. Results are usually more profound when they are also coupled with the standard of care, plus habit, lifestyle, and dietary changes.
However, it seems that any amount of resistance training is better than nothing. Based on this, it is likely that even low intensity, low frequency, resistance training programs have some positive effect on diabetes prevention and management. If you want a deeper dive into the nitty gritty of the science, check the sources linked below (15).
What Are The Current Strength Training Recommendation For Diabetes?
Current strength training guidelines for those with diabetes are lacking (8). Despite espousing the venerable merits of strength training, diabetes Canada only gives two main guidelines for resistance training for those with the disease:
Try to do at least 2 sessions per week of strength training (like exercises with weights or weight machines).
If you decide to begin strength training, you should ideally get some instruction from a qualified exercise specialist (18).
These are almost identical to the guidelines given to normal adults without diabetes (17). The problem is, they are non-specific, and likely to help very little in getting you started on a strength training plan with actionable steps. We can do better.
Instead, I offer you this plan, with these clear, delineated steps:
Download this template, my free home exercise template.
Run the program for 4 weeks.
Consider running the program for another 4 weeks, or until you get bored. Be consistent!
Once you get tired of this program, move onto a different program, or email me at Jonnyreps@gmail.com if you need ideas on what to do next.
All the while, you will get free emails from me to help you on your fitness journey.
Some Final Thoughts:
- Strength training and cardio are both good, but if you are going to choose just one, go with strength training. Strength training alone likely has a large impact on diabetic symptoms (19), and it also can yield many of the same benefits as cardio. The opposite is not necessarily true (16).
- Hypertrophy (muscle growth) seems to be one of the mechanistic reasons for reduction in diabetes risk / symptoms (8). Therefore, I would recommend that you not only focus on strength, but also on building some muscle for best results.
- Many people with diabetes do not know where to start. Up to 75% of diabetes patients do not get exercise guidelines from their doctor (10).
- The key to long-term improvements in your fitness is getting your foot in the door, and being consistent. Start small, and keep going.
- My free home workout program can help with many of these things, and more. It includes over 70 instructional videos, multiple variations for all exercises, and is fairly simple to follow for beginners. All you need is your body to get started. There are a few other things that can help like a backpack, a set of resistance bands, or a set of dumbbells that can be helpful, however, the entire program can be done with literally no equipment, if you don't have any.
I want to make exercise more accessible for everyone. I want people who feel like they have been not catered to in the fitness industry feel like they have simple and effective options for getting started today.
If you have any questions or need any help implementing the program, I'm here to help. And hey, if you want custom programming, or to work with me as your coach, you can apply here. I take applications regularly, so I will be in touch.
Thank you for reading the article, and I hope you gotten some practical takeaways. I hope you feel empowered to take control of your own health and fitness. If you have diabetes or know someone who does, please send them this article. It may help them find hope at the end of the tunnel, and get started on living a happier, healthier life.
Have a fantastic day, and I love you all!
Sources:
12.) https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/type-1-diabetes
17.) https://csepguidelines.ca/
19.) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161704/