Just when everyone was already confused about what types and amounts of training people with diabetes should be doing, along comes yet another study to muddy the waters some more. This latest exercise research was undertaken by faculty at McMaster University in Hamilton, Ontario, and appeared in the December 2011 issue of Journal of Applied Physiology (1).
The study involved eight individuals with type 2 diabetes (mean age of 63 years) who agreed to endure six sessions of high-intensity interval training done on a cycle ergometer over a two-week period. The training sessions consisted of 60 seconds of cycling done 10 times at ~90% of maximal heart rate, interspersed with 60 seconds of rest—for a total of only 10 minutes of actual exercise and 10 minutes of recovery. In other words, it involved almost an all-out sprint for a minute at a time, repeated 10 times with very little rest in between. Some call this low-volume, high-intensity interval training (HIT); others call it pure torture.
Before training and from ∼48 to 72 h after the last training bout, blood glucose responses were monitored using 24-hour continuous glucose monitoring. The exercise definitely had a positive effect on blood glucose levels: both the average levels over 24 hours and the 3-hour postprandial values after all three daily meals were improved significantly even 2-3 days after each training session, suggesting that low-volume HIT can rapidly improve glucose control and induce adaptations in skeletal muscle that improve metabolic health in people with type 2 diabetes.
While interval training is routinely used by sports teams and athletes, I have to question whether doing only this type of training would be beneficial for most individuals with diabetes. It certainly saves time—who can’t fit in 10 minutes of exercise three days per week?—but would it benefit weight control in the average person with type 2 diabetes? Probably not, as it simply doesn’t burn that many calories. Actually, it doesn’t save that much time either: when you add in the interspersed rest intervals and a warm-up and cool-down period, it still takes at least 25 minutes per session and 75 minutes per week. Current recs from the American Diabetes Association suggest that people with diabetes should try to get at least 150 minutes of moderate to vigorous exercise each week—an average of 30 minutes a day if done five days a week—so you’d only really be saving time on the two extra days you’re not doing the HIT routine.
There is no doubt that doing HIT training does have some benefits. This research suggests that doing thrice-weekly short intensive workouts may help lower blood sugar levels similarly to more frequently performed moderate activities. The sessions themselves dropped blood sugar levels from 137 mg/dL to 119 mg/dL, on average, which isn’t bad for only 10 minutes of exercise. In addition, overall and post-meal blood sugar levels were reduced long after training sessions were completed, which may or may not happen with more moderate workouts.
On the flip side, others who wrote articles about this training regimen also commented that “it requires so much suffering that you’re almost destined to quit.” Unless it’s regularly done with others, a coach, or a personal trainer to ensure motivation and positive feedback, most individuals will not have the drive to continue doing this type of training on their own long-term. What’s more, doing really intense exercise can actually cause a short-term elevation in blood glucose instead of a decrease, especially if the intense activity is not repeated enough times (such as the 10 sessions in this study) due to the effects of glucose-raising hormones released by sprinting. (So, you probably couldn’t stop early and gain the same benefits.)
If you can only do five to 10 minutes of exercise, that’s certainly better than nothing, but you really start to see the effects of exercise if you can regularly exercise harder and longer—for 20 to 30 minutes at least a few times a week. Another drawback of doing low-volume HIT is simply that not everyone is going to be able to do it, and it’s certainly not the best routine to start with when you’ve been sedentary for a while. It’s also more likely to result in overuse injuries and other joint problems that will stop you from doing anything after a while.
However, I’m totally in favor of routinely interspersing harder intervals into any regular training session—regardless of how easy or hard it is—both to increase cardiovascular fitness and to use up more blood glucose and stored carbohydrate (glycogen) in muscles, just like was done in one pilot study a few years back (2). Starting with easier workouts and interspersing slightly harder intervals into them is a lot more realistic for the majority of folks out there just getting started.
The bottom line: Just get up and off the couch to do any type of physical activity regularly, and your blood glucose levels will thank you.
References Cited:
(1) Little JP, Gillen JB, Percival ME, Safdar A, Tarnopolsky MA, Punthakee Z, Jung ME, Gibala MJ. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. J Appl Physiol. 2006;111(6):1554-60.
(2) Johnson ST, McCargar LJ, Bell GJ, Tudor-Locke C, Harber VJ, Bell RC. Walking faster: distilling a complex prescription for type 2 diabetes management through pedometry. Diabetes Care 2006;29:1654-5.
A lot of people with type 2 diabetes delay going on insulin for as long as possible because they’ve heard horror stories about how much weight it can make them gain (or maybe they just don’t like shots), but people with type 1 don’t have a choice. While it is true that insulin treatment is often associated with weight gain and more frequent bouts of hypoglycemia (low blood sugar), the real question is, why?
Some theories to explain insulin-induced weight gain are that when using insulin, your blood sugar is (usually) better controlled and you stop losing some of your calories (as glucose in your urine when your blood sugars exceed your urinary threshold) and that you may gain weight from having to eat extra to treat any low blood sugars caused by insulin. If you’re taking oral medications to lower your blood sugar and they are not working, however, insulin may be your main option for better control.
A few research studies have looked at whether weight gain is simply a result of eating more when you’re on insulin. One such study found that weight gain was not due to an increase in food intake, but rather that your body may increase its efficiency in using glucose and other fuels when your glycemic control improves—making you store more available energy from the foods you eat as fat (even if you’re eating the same amount as before you went on insulin) (1).
So, what can you do to avoid weight gain if you have to take insulin? First of all, you should try to keep your insulin doses as low as possible because the more insulin you take, the greater your potential for weight gain is. The best way to keep your insulin needs in check is to engage in regular physical activity. By way of example, some people with type 2 diabetes who were studied gained weight from insulin use while others did not. Interestingly, the main difference between the “gainers” and the “non-gainers” was that the gainers were less physically active (2). Moreover, in people with type 1 diabetes, taking insulin doses that effectively manage blood sugars can also lead to weight gain, but increases in activity levels have been shown to prevent getting fatter (3).
During any physical activity, your muscles can take up blood glucose and use it as a fuel without insulin and then following exercise, your insulin action is heightened for a few hours and as long as 72 hours—meaning that you will need smaller doses of insulin to have the same glucose-lowering effect. It is my personal experience that regular exercise is the best way to prevent insulin-induced weight gain, but your insulin doses will also need to be adjusted downward to prevent low blood sugars that cause you to take in extra calories to treat them.
Second, you may be able to avoid weight gain by taking a look at the type of insulin(s) that you are using. For example, in overweight type 2 diabetic subjects, use of once-daily Levemir (detemir) caused less weight gain and less frequent hypoglycemia than use of NPH (4), even combined with use of rapid-acting injections of a separate insulin for meals (and the same is likely true when using Lantus, or insulin glargine). Anyone taking basal insulin alone (once or twice daily) or following a basal-bolus regimen can benefit by making sure that insulin doses are regulated effectively to prevent blood sugar lows and highs—while using as little insulin as absolutely necessary to get the desired glycemic effect.
In other words, the type of insulin you use and the doses you take are both important to consider in the overall management of your diabetes and your body weight, regardless of which type you have. Just as importantly, though, is how you choose to manage your lifestyle, both your exercise and your dietary choices. Changes in your lifestyle, such as cutting back on refined carbohydrates that require larger doses of insulin to cover them and exercising regularly, are likely your best bets to counteract any potential weight gain caused by insulin use. An added side benefit is that if you have type 2 diabetes and start exercising regularly, you may actually lose fat weight and be able to lower your insulin doses more or get off of insulin injections completely.
References cited:
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