Increasing Insulin Sensitivity

No matter what your age, weight, or current level of physical fitness, studies have shown that exercise training can improve your insulin sensitivity within just one week of training without weight loss.

Types of training
While combined aerobic and resistance training is recommended for everyone, the benefits you will reap from any given activity will depend on how fit you currently are. If you’re completely sedentary now, starting a walking program or moderate resistance training program will initially be effective enough. If you’re already doing regular aerobic exercise, you will likely benefit more from adding some interval training or resistance training to your exercise routine. In interval training, you intersperse periods of intense exercise with periods of slower, easier activity. For example, on a stationary bike, you might pedal faster and harder for 30–60 seconds, then pedal at a moderate pace for a few minutes, then repeat this pattern throughout your exercise session.

Once again, research confirms that this approach works. In a recent study of previously sedentary people with Type 2 diabetes, four to six weeks of moderate-intensity resistance training improved their insulin sensitivity by 48%, even without causing any significant changes in their body fat or muscle mass. Similarly, unfit men who were newly diagnosed with Type 2 diabetes who did 16 weeks of “progressive” resistance training (meaning that the weight they lifted was increased over time) just twice a week gained muscle mass, lost body fat (particularly in the abdominal region), and greatly enhanced their insulin sensitivity — all despite a 15% increase in the amount of calories they consumed.

For older women with Type 2 diabetes, studies have shown that the combination of aerobic and resistance training may afford even greater improvements in insulin sensitivity and a more significant decrease in abdominal fat than aerobic training alone, with increased muscle mass to boot.

Maximizing the effects
The exercise studies mentioned so far all examined the effects of longer-term training, but each bout of exercise also exerts its own effect. During exercise, your body burns glycogen, a form of glucose that is stored in your muscles. After exercise, your muscles replenish their glycogen stores with glucose from the bloodstream. The more glycogen that is burned during a bout of activity, the longer the body’s insulin sensitivity is improved.

More intense and longer-duration activities can improve insulin sensitivity for up to one to two days, as muscle glycogen that was used during the exercise is being restored. A short, low-intensity activity such as weeding a small garden, however, may not have any lasting impact on insulin sensitivity since very little glycogen is used during it.

Therefore, to improve insulin sensitivity on a continuing basis, you should plan on exercising at least every other day, with near-daily workouts exerting an even more beneficial effect. In addition, you should try to do some more intense workouts (like brisk walking and resistance work) in addition to normal, less strenuous daily activities.

For example, in a recent study of older individuals with diabetes, even when they were already walking at least 10,000 steps a day, their fitness and diabetes control benefited from doing “pick up the pace” training that consisted of walking at a 10% faster pace for 30 minutes three days a week. For a person who usually takes 90 steps per minute, walking 10% faster would mean taking 99 steps per minute instead.

Planning your daily activities
Given that the effects of more intense or longer-duration exercise may last slightly longer, the best plan is to intersperse these types of workouts throughout your week, or to do a more intense activity every other day to maximize its insulin-enhancing effects. Alternating between more challenging activities and easier or more moderate activities is a good way to keep yourself motivated, prevent athletic injuries, and keep your exercise training on track.