Resistance Training: A Key Strategy to Manage Prediabetes & Type 2 Diabetes?

Type 2 diabetes is a deadly disease that affects over 400 million people worldwide. It accounts for around 90% of all cases of diabetes, and has an estimated annual global cost of 1.3 trillion dollars (1).

It is linked to premature mortality and significant morbidity, which occurs primarily from hyperglycemia-induced cardiovascular disease and microvascular complications including neuropathy, nephropathy, and retinopathy (2). 

Prediabetes is a condition defined as elevated blood glucose levels but are still below the level considered to be type 2 diabetic. Prediabetes has impacted over 352.1 million people worldwide in 2017 (3).

This condition often leads to metabolic syndrome, a state characterized by multiple issues including insulin resistance, abdominal obesity, hypertension, and dyslipidemia (unhealthy levels of one or more kinds of fat in your blood) (4).

Metabolic syndrome and prediabetes increase the risk for developing chronic diseases such as type 2 diabetes and cardiovascular diseases, as 5–10% of those with prediabetes progress to type 2 diabetes annually (4). 

Treatment strategies, such as lifestyle modifications, that address abnormal metabolic risk factors, such as glycosylated hemoglobin (HbA1c), fasting plasma glucose, and blood lipids, can reduce rates of progression to type 2 diabetes (5).

Below we’ll take a look at the pathophysiology of type 2 diabetes and the impact of exercise, specifically resistance training in managing this disease. 

The following are key points in the clinical diagnosis of Type 2 diabetes:

• A person’s fasting blood glucose levels are greater than or equal to 126 mg/dL or blood glucose levels greater than or equal to 200 mg/dL after an oral glucose tolerance test. 
• Diagnosis of “pre-diabetes” can be made when fasting blood glucose levels are between 100 and 125 mg/dL or blood glucose levels are between 140 and 199 mg/dL after an oral glucose tolerance test. 
• HbA1c levels (typically referred to as the A1c test) is utilized in order to assess a person’s glycemic response over time. This test is frequently measured in research that investigates the effect of exercise on type 2 diabetes (6).
• HbA1c is a type of hemoglobin that reacts with plasma glucose to form a glycoprotein and is elevated in individuals with diabetes. 
• American Diabetes Association now recognizes HbA1c levels greater than 6.5 mg/dL as a clinical biomarker for the diagnosis of type 2 diabetes (7).

Benefits of Resistance Training 

Both aerobic and resistance training programs have been shown to be effective at managing and preventing type 2 diabetes.

Resistance training is purported to help decrease the risk of type 2 diabetes by increasing muscle mass, utilization of glucose, and control of enzymes involved in glucose metabolism (8).

Resistance training, independent of aerobic exercise habits, was recently shown to be associated with a 34% decreased risk of developing type 2 diabetes (9). 

However, combining both aerobic exercise and resistance training showed the greatest reduction in risk of type-2 diabetes (59%).

The evidence that resistance training alone has such an impact on type 2 diabetes is encouraging for those individuals who find it difficult to adhere to an aerobic exercise schedule. 

The primary goal of resistance exercise in the management of type 2 diabetes is to improve glycemic control. 

Secondary goals include increased lean body mass, increased strength, and reduction in associated comorbidities, and appropriate intensity, progression, and program length are critical for influencing glycemic control (10). 

These recommendations were based on progressive high-intensity resistance training programs that were able to significantly decrease HbA1c levels in people with type 2 diabetes (11), and a decrease in HbA1c is a clinically significant sign of improving glycemic control. 

Comprehensive review on resistance training & type 2 diabetes

A very recent comprehensive meta-analysis examined the effects of resistance training on cardiometabolic health in adults at risk for type 2 diabetes.

In addition, for this information to be implemented in daily practice for clinicians to utilize, this research also examined which characteristics of resistance training programs are correlated with improved cardiometabolic outcomes (12).

Major findings of this meta-analysis were that resistance training can reduce HbA1c and fasting plasma glucose in individuals at risk for developing type 2 diabetes.

Therefore, resistance training is effective for improving glycemic control and blood lipid profiles in adults at risk for type 2 diabetes and could serve as an effective intervention to prevent or delay the onset of type 2 diabetes.

Resistance training can and should be recommended by clinicians in order to improve cardiometabolic outcomes of their patients (12). 

As far as characteristics of resistance training programs; free weight and resistance band training at intensities above 60% one-repetition maximum are effective for improving glycemic control and blood lipid profiles in adults at risk for type 2 diabetes.

Although the findings also suggest that resistance training may improve blood lipid profiles, and that a dietary component combined with resistance training did not result in larger reductions in fasting plasma glucose and triglycerides than resistance training alone, more studies in the future are needed to confirm these findings (12).

Proposed research-based mechanisms by which resistance training improves glycemic control:

1. Improved glycemic control is because of increased muscle mass and subsequent increased muscle glycogen, which is shown in individuals with type 2 diabetes performing resistance training (11).

2. Better insulin sensitivity and control of membrane transporters (e.g. GLUT4) are responsible for improved glycemic control in these people (13).

Regardless of the proposed mechanism, resistance training helps manage type 2 diabetes due to the increased utilization of glucose.

More glucose is stored in muscle tissue as glycogen which results in less blood glucose available to bind with hemoglobin; therefore lowering HbA1c levels.  

The following are key objectives in regards to exercise complications and medical management: 

• Clients with type 2 diabetes should be evaluated by a medical professional before beginning a new exercise program. This evaluation should include pertinent information about the client’s level of glycemic control, current medications, exercise contraindications, and other precautions associated with an exercise program. 
• Exercise-induced hypoglycemia is one of the most common risk factors for individuals with type 2 diabetes, especially those taking insulin and/or other blood-glucose controlling medications (7). 
• There is an absolute contraindication of exercise if blood glucose is less than 70 mg/dL.
• Hypoglycemia releases many hormones (e.g., glucagon, epinephrine, cortisol, growth hormone) which can lead to a variety of physiological responses such as hunger, sweating, nervousness, dizziness, confusion, anxiety, weakness, and increased pulse. 
• Hypoglycemic individuals are advised to consume 15-20 g of carbohydrates (fruit, fruit juice, or sport drink/bar) until glucose values stabilize (7). 
• Hyperglycemia is considered a characteristic of type 2 diabetes and not considered a risk factor. Individuals with blood glucose levels more than 300 mg/dL without ketones, can still participate in exercise as long as they are properly hydrated and feel well (7). 
• Comorbidities that are present in people with type 2 diabetes include macrovascular disease, hypertension, dyslipidemia, retinopathy, neuropathy, and nephropathy.
• Trainers should be aware that acute bouts of resistance training can significantly elevate blood pressure, heart rate, and cardiac output, especially during the eccentric phase (i.e. lengthening of muscle under tension) of exercise or when the Valsalva maneuver is utilized.
• High-intensity exercise is contraindicated for those with proliferative retinopathy because of possible retinal hemorrhaging.
• People with loss of sensation (peripheral neuropathy) in their feet should not conduct high-impact activities including running, jumping, heavy walking and some resistance training exercises.

In summary

Resistance training can improve glucose tolerance and insulin sensitivity independently of the increase in muscle mass. It is well known that insulin sensitivity is directly proportional to lean body mass.

The increase of lean mass remains a reasonable goal for prediabetic and type 2 diabetic individuals performing resistance training.

I also highly recommend Steel’s ADA-LOAD to assist with blood glucose regulation for this population. 

ADA-LOAD is a nutrient partitioning agent designed for adding muscle mass and size, increasing energy and muscle pumps. It works by driving the nutrients into the muscle and creating an anabolic environment within your body.

Essentially, ADA-LOAD is a combination of ingredients shown in evidence-based research to reduce blood sugar levels in individuals with high blood glucose.

In today’s society, it’s difficult for the average person to commit to exercising for long periods of time. 

Another option is to perform short-repeated exercise as a viable alternative to the traditional high-volume endurance training. High-intensity/low-volume resistance training can be an efficient strategy to obtain metabolic benefits.

The bottom line is that resistance is extremely effective at managing hyperglycemia for clients with type 2 diabetes. The end result leads to a better utilization of blood glucose within the muscle cell, which is the goal of anyone with type 2 diabetes. 

References:

1. Bommer, C., Heesemann, E., Sagalova, V., Manne-Goehler, J., Atun, R., Barnighausen, T., and Vollmer, S. (2017) The global economic burden of diabetes in adults aged 20-79 years: a cost-of-illness study. Lancet Diabetes Endocrinol 5, 423-430

2. Chawla, A., Chawla, R., and Jaggi, S. (2016) Microvasular and macrovascular complications in diabetes mellitus: Distinct or continuum? Indian J Endocrinol Metab 20, 546-551

3. Hostalek, U. (2019) Global epidemiology of prediabetes - present and future perspectives. Clin Diabetes Endocrinol 5, 5

4. Tabak, A. G., Herder, C., Rathmann, W., Brunner, E. J., and Kivimaki, M. (2012) Prediabetes: a high-risk state for diabetes development. Lancet 379, 2279-2290

5. Gami, A. S., Witt, B. J., Howard, D. E., Erwin, P. J., Gami, L. A., Somers, V. K., and Montori, V. M. (2007) Metabolic syndrome and risk of incident cardiovascular events and death: a systematic review and meta-analysis of longitudinal studies. J Am Coll Cardiol 49, 403-414

6. Eves, N. D., and Plotnikoff, R. C. (2006) Resistance training and type 2 diabetes: Considerations for implementation at the population level. Diabetes Care 29, 1933-1941

7. American Diabetes, A. (2011) Standards of medical care in diabetes--2011. Diabetes Care 34 Suppl 1, S11-61

8. LeBrasseur, N. K., Walsh, K., and Arany, Z. (2011) Metabolic benefits of resistance training and fast glycolytic skeletal muscle. Am J Physiol Endocrinol Metab 300, E3-10

9. Grontved, A., Rimm, E. B., Willett, W. C., Andersen, L. B., and Hu, F. B. (2012) A prospective study of weight training and risk of type 2 diabetes mellitus in men. Arch Intern Med 172, 1306-1312

10. Colberg, S. R., Sigal, R. J., Fernhall, B., Regensteiner, J. G., Blissmer, B. J., Rubin, R. R., Chasan-Taber, L., Albright, A. L., Braun, B., American College of Sports, M., and American Diabetes, A. (2010) Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement executive summary. Diabetes Care 33, 2692-2696

11. Castaneda, C., Layne, J. E., Munoz-Orians, L., Gordon, P. L., Walsmith, J., Foldvari, M., Roubenoff, R., Tucker, K. L., and Nelson, M. E. (2002) A randomized controlled trial of resistance exercise training to improve glycemic control in older adults with type 2 diabetes. Diabetes Care 25, 2335-2341

12. Qadir, R., Sculthorpe, N. F., Todd, T., and Brown, E. C. (2021) Effectiveness of Resistance Training and Associated Program Characteristics in Patients at Risk for Type 2 Diabetes: a Systematic Review and Meta-analysis. Sports Med Open 7, 38

13. Holten, M. K., Zacho, M., Gaster, M., Juel, C., Wojtaszewski, J. F., and Dela, F. (2004) Strength training increases insulin-mediated glucose uptake, GLUT4 content, and insulin signaling in skeletal muscle in patients with type 2 diabetes. Diabetes 53, 294-305