Yes, yes, most definitely yes.
I am sure most of us have heard the term "diabetes" or "Type II diabetes" and know it's associated with our blood sugar and insulin, but we may not be quite sure what it is exactly. 90-95% of all diabetes mellitus cases are Type II, which results from the muscle cells becoming resistant to insulin and the body's inability to compensate for this resistance (insulin helps the body's cells take in sugar for food). What's the big deal with having a high level of blood sugar (blood glucose)? Type II diabetes is a significant cause of early death and sickness related to cardiovascular disease, blindness, kidney disease, nerve disease, and amputation . So, it is a big deal, and definitely not something to take lightly.
Genetic and environmental factors play a huge role in the development of diabetes, and it has yet to be teased out with a fine-tooth comb how much each contributes. However, we do know that the risk for diabetes increases with age, obesity, and physical inactivity. While we might not be able to control our genetics or our age, we can most definitely control our weight and physical activity level.
Does weight loss and physical activity really matter when there's medication I can take? Absolutely. The Diabetes Prevention Program (DPP) investigated the difference in reduction of the incidence of Type II diabetes between lifestyle intervention (diet and exercise) versus medication (metformin) versus a control group. And guess which one came out on top? That's right, the lifestyle intervention. In fact, the lifestyle intervention group actually reduced the risk by a whopping 58% as compared to only 31% by the medication group . That's a whole 27%!
How does that even happen? Quick science lesson:
During rest and after eating, the muscle cells are dependent on insulin to be able to take in glucose from the blood. They need this glucose to replace their glycogen stores in order to keep functioning. During exercise, the muscle contractions allow the muscle cells to increase their uptake of blood glucose without the help of insulin. These two pathways are separate, thus even when the insulin-needy pathway is impaired by diabetes, the blood glucose uptake still functions normally during exercise.
Exercising can have both immediate and long term effects on a person's blood glucose levels. One bout of moderate-intensity exercise can cause an increase in insulin action and glucose tolerance for 2-72 hours afterwards (varies by the duration and intensity of the exercise). Over time, exercise training can improve insulin action, blood glucose control, and fat oxidation and storage in muscle (which is better than in fat cells). However, any exercise program must be performed regularly to have a continued effect.
So now that we know physical activity is excellent at helping to prevent and treat diabetes, what kind of exercise do we need to be doing ?
- Moderate-intensity aerobic (such as brisk walking) and resistance training (such as weight lifting)
- Either alone will work, but performing both gives the best results
- Milder forms of exercise, such as tai chi and yoga, have shown mixed results, and up to this point should not substitute aerobic or resistance training
- Aerobic Exercise
- At least 150 minutes of moderate to vigorous activity spread out over at least 3 days per week
- Bouts can be no shorter than 10 minutes
- No more than 2 days should elapse between workouts
- If relying on exercise alone for weight loss purposes, up to 60 minutes per day may be necessary
- All aerobic exercise should be at moderate intensity (40-60% of your max heart rate), although progressing to vigorous activity can help to obtain additional blood glucose benefits
- Any form of aerobic exercise is fair game (including brisk walking), as long as it causes a sustained increase in heart rate
- Resistance Training
- At least two times per week, optimally 3 on nonconsecutive days
- All resistance training should be at moderate (50% of your 1-repetition max) or vigorous (75-80% of 1-repetition max) intensity
- Training should minimally include 5-10 exercises involving the major muscle groups (in the upper body, lower body, and core)
- In the beginning these sets (as low as 1) should consist of 10-15 repetitions to near fatigue in each set
- As progression occurs, the weight should be increased until only 8-10 repetitions can be performed per set (as many as 3-4 sets)
- Resistance machines and free weights are the recommended modes for resistance training
- It is also strongly recommended that the training be supervised (by a trainer or other health professional) for the best results
Now there are also some warnings that need to be addressed, especially for people with advanced diseases, with uncontrolled blood glucose, or those already dependent on insulin. For those with advanced diseases and uncontrolled blood glucose levels, you can still exercise and reap the benefits. However, first have a chat with your physician to see if additional testing needs to be done and if you have any exercise restrictions. For those diabetics already taking insulin, it is imperative that you monitor your blood glucose levels before, after, and possibly during (if just starting) exercise. Depending on which insulin you are taking, it could be necessary to ingest carbohydrates prior to exercise to prevent hypoglycemia. Once again, this is a time to talk with your physician to see how much you need to take and when.
If you find yourself faced with the diagnosis of pre-diabetes or diabetes, talk to your doctor about what you can do to make lifestyle changes to help lower your blood glucose levels.
 American College of Sports Medicine and American Diabetes Association Joint Position Statement: Exercise and Type 2 Diabetes. Med Sci Sport Exer. 2010;42(12):2282-2303.
 Knowler WC, Barrett-Connor E, Fowler Se, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403.