Ashley Dunworth, RD
We all know that exercise is good for a strong body. Exercise can help maintain
healthy weight, increase lean muscle mass and therefore boost metabolism. But
did you also know that exercise can lower blood sugar levels AND increase insulin
sensitivity? The benefits of exercise are endless- no one ever says: “I really regret
walking today.” That’s because exercise is never regrettable! When it comes to
improving mood, losing weight, sleeping better and especially controlling
diabetes, exercise is an all around win-win!
What kind of effect does exercise have on blood glucose?
Our first source of energy for muscles is glucose. When we are active, our muscles
expand and contract. During this type of movement, our muscle cells have the
ability to uptake glucose through active transport without the use of insulin (1).
This process increases energy metabolism thus decreasing glucose free- floating in
the blood. Alongside increased cellular glucose uptake, insulin sensitivity is also
improved. When insulin can effectively attach to cells, it signals muscle and
adipose tissue to uptake glucose, while also signaling the liver to stop glucose
release (gluconeogenesis) (1). These actions together increase glucose uptake and
ultimately increase energy production.
What does the literature show? In a 16-week study on the effect of exercise on
insulin resistance in 60 Latino adults, there was a statistically significant decrease
in A1C concentrations (p=0.01) as well as decrease in serum triglycerides (p=0.08),
and in systolic blood pressure (p=0.05) (2). Muscle glycogen was also measured
and showed an increase in muscle storage of glucose (p=0.008) (2). The
intervention for this study was in the form light, resistance training exercise, 45-
minutes, 3 times per week, compared to the control that did not participate in any
form of exercise the duration of the study. This study shows supportive evidence
that exercise can considerably improve glycemic control, increase energy
metabolism and have the added benefit of reducing blood pressure and free
floating triglycerides in the blood (2).
Another study with 54 women over a 14-week period showed that exercise was
able to significantly metabolize glucose in the blood (p<0.001). Insulin sensitivity
was also significantly increased with exercise (p<0.008) compared to the control
(3). This study, along with dozens found in the literature, contains reassuring evidence of the positive effects exercise has on glycemic control and diabetes.Is there a downside to exercise with diabetes?
Before running out and hitting the gym, it is important to understand how exercise
can affect blood glucose (BG) on an individual level. Because exercise, specifically resistance
training, can increase lean muscle mass, the metabolism effects can last up to 24 hours.
To be safe- it is imperative to be consistent with checking BG levels before and after physical
activity in the start of any new exercise routine to understand how it affects BG levels.
Hypoglycemia is possible during exercise and it is important to be prepared (4): Always keep a fast-release glucose snack on hand, 15-20g carbohydrate (e.g., candy, soda, juice,
glucose tablet). Test glucose 20-30 minutes after, if still low, eat another carbohydrate snack and repeat testing. When exercising, in most cases, it is not necessary to increase the amount of carbohydrates consumed per day, BUT- it is important to check blood sugar and
thoroughly understand how exercise affects glucose levels. Before starting any new exercise
routine, always check with a doctor first! How to get the most benefits from exercise: Strategically planning exercise throughout the day is most valuable. Time is always an issue, and gym memberships can by pricey. Taking short walks (10-15 minutes) before and after meals can increase insulin sensitivity and help lower BG levels. In fact, short bursts of physical activity spread
throughout the day can help with diabetes control (4). Exercise in all forms, whether
walking, taking the stairs, doing lunges in the office or even cleaning the house, can
help keep BG levels maintained. Not only will exercise benefit diabetes maintenance,
but it also improves overall health by aiding in weight loss, reducing blood pressure
and increasing energy. The bottom line—get out and get active!