Type 2 diabetes is the most common form of diabetes, characterized by hyperglycemia, insulin resistance, and impairments in insulin secretion. Having sufficient levels of physical activity can prevent the onset of type 2 diabetes and help to manage its symptoms.
Resistance training is a form of exercise that improves insulin sensitivity through increased glucose uptake and clearance and increased muscle size—thus reducing the risk of developing pre-diabetes or type 2 diabetes.
How to optimize your resistance training workout
I like to provide information on optimization because a lot of times people are not sure what to do in regards to strength training. A frequent question is “how much do I need to do?” However, extrapolating an exact optimal dose of resistance training for diabetes prevention is challenging.
First, this is because resistance training has a very specific outcome— muscle strength and growth.
Muscle strength is associated with diabetes risk reduction. Muscle growth enhances the capacity of glucose use.
Second, resistance training has many components which include exercise selection, frequency of training, duration of training, intensity (how heavy the weight is), total volume (sets x reps x weight), and rest periods.
So, we can think of the impact of resistance training in terms of how often you do it and then the positive physiological results that come with participation.
How heavy should I lift to prevent diabetes?
A 2019 review examined the influence of intensity on markers of diabetes. Researchers found both low-to-moderate intensity and high intensity resistance training had positive effects on HbA1c levels in diabetics. But the decreased HbA1c with high intensity was greater than that observed in the low-to-moderate intensity groups. Only high intensity training was associated with reduced insulin. Both high intensity and low-intensity resistance training reduces blood glucose.
These results suggest that lifting heavier loads may have specific beneficial effects on markers of diabetes. These authors considered intensities between 20% and 75% of a person's max as low-to-moderate intensity and between 75% and 100% 1RM as high intensity.
The good news is that this means you do not need to max out on a lift but working at intensities where you can do 10 reps or less would be beneficial to be in parts of your program.
What Duration Should I Lift For?
A 2012 study out of the Harvard school of public health  examined the association of weight training with the risk of type 2 diabetes in men over the course of 18 years. In this period, they documented 2,278 new cases of diabetes (out of 51,529 participants).
The researchers found that performing weight training 1 to 59, 60 to 149, and at least 150 minutes per week had a reduced risk of 12%, 25%, and 34% respectively, compared with reporting no weight training. These results were independent of aerobic training (although engaging in aerobics further reduced the risk).
A 2014 study by the same author found that compared to women engaging in no muscle-strengthening, those engaging in 1–29, 30–59, 60– 150 and ≥150 min/week had 24%, 6%, 31%, and 37% lower risk of type 2 diabetes.
This suggests that higher durations provide more benefits but that any resistance training is better than none.
Lift more often to see health improvements
The American Diabetes Association recommends that people engage in strength training on 2-3 non consecutive days of the week.
A 2012 study found that participants who did strength training once per week or two or more times per week had 47% and 27% lower odds of having impaired glucose metabolism.
A large scale cross-sectional study found that the lowest odds of having diabetes was among those reporting strength training three to four times/week.
So, it is likely that any dose is beneficial, although more may be better.
How many reps and sets should I do?
Based on the previous research I have covered, we can extrapolate some ideas for specific sets and rep prescription. First, it seems that any duration is beneficial, especially if you are not currently doing strength training. Second, it seems that higher intensities may be more beneficial.
Let’s imagine that a single set of 10 repetitions when including rest takes about 1 minute. 60 minutes of weekly strength training is associated with significant reductions in the risk of diabetes, so over the course of the week, you should shoot for at least 60 total sets of any exercise.
Let’s imagine that you decided to do 10 exercises per session over two sessions for a total of 20 exercises. One set of 10 repetitions would be about 20 minutes in the week. So to get 60 minutes 3 sets would be a good place to be.
A 2017 review found that a program with 21 or more sets per session had a larger effect on glycemic control than one with fewer than 21 sets per session. So I believe that this supports this idea —although it seems that less than 30 sets (10 exercises, 3 sets) certainly has benefits.
Of course, you could achieve this in any number of ways so this is just a recommendation. If you’re new to strength training you can cut this down and work up to that.
From here, let’s end on muscle strength and see if there are cut off values to work towards.
Muscle strength can lower diabetes risk
Muscle strength is a primary outcome of resistance training, particularly at higher intensities. Strength can also be objectively measured so it is good to see where you stand in order to gauge risk.
A 2020 study examined age- and sex-specific thresholds of muscular strength, for prediabetes and diabetes risk categorization among apparently healthy U.S. adults.
Young adults were classified as those 20–50 years of age. Older adults were older than 50. Normalized grip strength was assessed by determining how much force participants could create on a hand grip test divided by their weight.
For example, if I weigh 86 kg and can produce 60 kg of force my normalized grip strength is 0.70. The authors found the following cut points for detecting diabetes risk included
- 0.78 (young male participants)
- 0.57 (young female participants)
- 0.68 (older male participants)
- 0.49 (older female participants).
If you have the opportunity to test your hand grip, you can see where you land. If you are below these cut points you may want to put a premium on improving your muscular strength.
Minimum dose and optimal dose of resistance training
We can think of those doses of resistance training in terms of a minimum dose and an optimal dose. A minimum dose would be where the risk of diabetes starts to decline. It would seem that any dose reduces the risk. So, if you are currently not doing resistance training, just starting and staying consistent will reduce your risk. If your levels of strength are above the cut points that is also a good indication that you have at least the minimum dose of strength.
An optimal dose is the point where maximum benefits begin to accrue. I would recommend shooting for three days of strength training, in rep ranges of 8-15, for at least 21 total sets. In terms of weekly duration, more than 60 minutes seems optimal. Thus, for optimal doses I would recommend three days for at least 30 minutes per session.
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