Exercise as it relates to Disease/Insulin Resistance: The effect of exercise to reduce Metformin dependence
Insulin resistance is an impaired ability of insulin to stimulate glucose consumption. This difficulty in accurate insulin function can be the first stages of type 2 diabetes. Insulin resistance is also a risk factor for cardiovascular disease. Metformin: An anti-diabetic drug (trade name Glucophage) prescribed to treat type II diabetes it is used in conjunction with diet and exercise and may be used alone or with other anti-diabetic medicines. It is a biguanide antidiabetic, which works by decreasing the amount of sugar that the liver produces and the intestines absorb. Metformin also helps the body’s sensitivity to insulin produced naturally. Exercise is a very effective treatment for insulin resistance, and is effective in reducing dependence on metformin. Studies show that insulin sensitivity increased significantly for 16 hours after one-hour exercise session with and without Metformin.
Effects of Exercise
- Reduction in adipose tissue which has been linked to exacerbation of insulin resistance and fat storage.
- Increased insulin sensitivity with the same effectiveness as Metformin.
- Reduction in visceral fat (where insulin dependent people tend to store fat).
- Reduction in subcutaneous fat.
- Increased oxygen capacity and oxygen levels in the blood.
- Increased fitness which lowers blood pressure.
- Reduction in hyperglycemia.
- Psychological benefits such as improvements in self-efficacy.
- Reduction in some depression symptoms.
- Load bearing on joints and muscles during and post exercise.
- Muscle and joint pain.
- Insulin resistance is a symptom or is comorbid with diseases such as Polycystic Ovarian Syndrome (PCOS), Obesity, Cardiovascular disease, Metabolic Syndrome, Hypertension.
- Inhibition of performance by prescribed medication.
Aerobic and resistance training have both individual and combined positive effects, leading to the general prescription of combined exercise for people with insulin resistance.
The effects of aerobic exercise
- Weight loss/ BMI reduction.
- Transition of LDL to HDL- improving cholesterol.
- Improved oxygen capacity.
- Increased fitness.
- Reduced heart rate and blood pressure.
The effects of resistance exercise
- Decreased waist circumference.
- Decreased fat percentage but no effect on weight loss.
- Increased VO2Max.
- Decreased insulin resistance even when there is no fat loss.
Moderate and high intensity exercise has similar effects on insulin resistance. Although high intensity exercise is beneficial for decreasing LDL cholesterol, there is a high risk of injury and non-adherence. High intensity exercise also puts clients with comorbidities i.e. cardiovascular disease at high risk of complications. Moderate intensity is generally prescribed, as clients are more likely to adhere to a moderate exercise regime.
Aerobic and resistance training are both beneficial to insulin resistance. They contribute to fitness, metabolic functions and body/fat composition. Strength and fitness allow the optimum, well-rounded workout to decrease risk factors and lower insulin resistance. Precautions and monitoring of the individual are suggested as there are several risk factors involved. Metformin can hinder exercise performance by increasing heart rate, which increases the risk factor. Metformin also decreases the glucose lowering effect of exercise. Comorbidities with insulin resistance as mentioned above also need consideration for the prescription of exercise in place of or together with the use of metformin for insulin resistance.
- Kahn CR, 1994, Insulin action, diabetogenes, and the cause of type II diabetes. Diabetes. Vol 43: 1066-1084
- McFarlane SI, Banerji M, & Sowers JR. 2001, Insulin resistance and cardiovascular disease. J Clin Endocrinol Metab. Vol 86:713-8
- Gray S & Kim J.K. (2011). Trends Endocrinol Metab. Vol 22, no.10: 394 - 403
- Borghouts, L. B. & Keizer, H. A. 2000, Exercise and insulin sensitivity: a review. International Journal of Sports Medicine, 21: 1–12
- O'Leary, V. B., Marchetti, C. M., Krishnan, R. K., Stetzer, B. P., Gonzalez, F. & Kirwin J. P. 2006
- Ross, R., Janssen, I., Dawson, J., Kungl, A. M., Kuk, J. L., Wong, S. L., Nguyen-Duy, T. B., Lee, S., Kilpatrick, K. & Hudson, R. 2004, Exercise-induced reduction in obesity and insulin resistance in women: a randomized controlled trial. Obesity Research, 12, 789-798
- Boule, N. G., Robert, C., BELL, G. J., Johnson, S. T., Bell, R. C., Lewanczuk, R. Z., Gabr, R. Q. & Brocks, D. R. 2011, Metformin and exercise in Type 2 diabetes: examining treatment modality interactions. Diabetes Care, 34, 1469-1474
- Van Dijk ,J. W., Manders, R. J. F., Tummers, K. Bonomi, A. G., Stehouwer, C. D. A., Hartgens, F. & Van Loon, L. J. C. 2011, Both resistance and endurance type exercise reduce the prevalence of hyperglycaemia in individuals with impaired glucose tolerance and in insulin-treated and non-insulin treated type 2 diabetic patients. Diabetologia, 55, 1273-1282
- O’Donovan, G., Kearney, E. M., Nevill, A. M., Woolf-May, K. & Bird, S.R 2005, The effects of 24 weeks of moderate- or high-intensity exercise on insulin resistance. European Journal of Applied Physiology, 95, 522-528