Up to 70 percent of North Americans adults will develop diabetes or pre-diabetes, usually from insulin resistance caused by excess fat in the liver and muscles. Exercise helps to empty fat from the liver and muscles, so exercise helps to prevent and treat diabetes.
Nearly 69,000 men and women with no diabetes or heart problems were tested for heart fitness by running on a treadmill (American J of Medicine, January 9, 2020). Insulin resistance was measured by a fasting blood sugar greater than 100 mg/dL and triglycerides greater than 150mg/dL.
Compared to non-obese fit people, those who were:
• unfit women and men who were not overweight had more than double the risk of insulin resistance
• fit but obese women had 11 times the incidence of insulin resistance
• unfit and obese women had more than 20 times the incidence of insulin resistance
• fit but obese men had 7.4 times the incidence of insulin resistance
• unfit and obese men had 12.9 times the incidence of insulin resistance
Definition of Insulin Resistance
Insulin drives sugar, fat and protein into cells. Insulin resistance means that the cells do not respond to insulin, so sugar builds up in the bloodstream. Everyone’s blood sugar rises after they eat, but if blood sugar rises too high, sugar irreversibly sticks to cells and can destroy every kind of cell in your body. To prevent blood sugar from rising too high, your pancreas releases insulin into your bloodstream, which lowers blood sugar by driving sugar from the bloodstream into the liver. However, if the liver is full of fat, it does not accept the sugar and blood sugar levels rise even higher. Insulin resistance can be reversed by emptying fat from the liver and muscles.
Use Both Aerobic Exercise and Resistance Exercise to Combat Insulin Resistance
• The larger your muscles, the less likely you are to become insulin resistant. High blood sugar causes loss of muscle size (JCI Insight, February 21, 2019;4(4)).
• Six weeks of resistance exercise improves insulin sensitivity in young, overweight men (Experimental Physiology, Feb 1, 2019).
• A review of 105 studies shows that a regular exercise program lowers fasting blood sugar and HBA1c (which measures the amount of sugar stuck on cells) in both diabetics and non-diabetics, and that each additional 100 minutes per week of physical activity was associated with a mean average decrease of 2.75 mg/dL of fasting blood sugar (Acta Diabetol, (2017) 54:983).
• Strength training lowers high blood sugar levels and liver fat, even before weight loss occurs (Journal of Endocrinology, Apr 2019;241(1):59–70).
Intense Exercise Lowers HBA1c
• A review of eight studies on 235 participants who exercised from 12 weeks to six months found that the greater the intensity of exercise, the greater the lowering of HBA1c, a measure of cell damage from high blood sugar levels (Acta Diabetol, June 17, 2016).
• A review of 47 studies of 8,538 patients who exercised more than 12 weeks for more than 150 minutes per week, showed a significant reduction of HBA1c (JAMA, Nov 24, 2010;304(20):2253-62; JAMA, May 4, 2011;305(17):1790-9).
• A study of 262 sedentary middle-aged men and women, with type 2 diabetes and HBA1c levels of 6.5% or higher, found that a combination of aerobic and resistance training (three days a week for nine months) improved HBA1c levels, compared with a non-exercising control group. This was not achieved with aerobic or resistance training alone (JAMA, Mar 2, 2011;305(9):892).
• A review of 12 studies of 2-6 months of exercise in diabetics found that aerobic exercise reduced HBA1c more than resistance exercise, and the greater the weight loss, the greater the drop in HBA1c, peak oxygen consumption, and maximum heart rate. The authors felt that aerobic and resistance exercises were equal in helping to prevent heart attack risk factors (Sports Med, Apr 2014;44(4):487-99).
Most cases of diabetes are caused by insulin resistance which usually comes from excess fat in the liver and muscles. Both aerobic and resistance exercise help to prevent and treat diabetes by helping to empty the liver and muscles of excess sugar. Exercise helps to reduce excess weight, high blood pressure, high LDL cholesterol, and high triglycerides. Exercise also helps to increase healthy HDL cholesterol, strengthens muscles and bones, and combats depression.