High blood sugar increases risk of type 2 diabetes
Physical activity helps control blood sugar
Aerobic exercise reduces the risk of cardiovascular disease and type 2 diabetes. A review 26 studies by Italian researchers showed that the timing of aerobic exercise mattered with respect to diabetes. Chronic elevated levels of blood glucose (sugar) and triglycerides (blood fats) predict elevated risk of insulin resistance and type 2 diabetes. Pre-meal exercise appeared to reduce triglyceride levels but not blood glucose levels in healthy patients. Pre-meal exercise also helped limit weight gain and reduce triglyceride-induced insulin resistance in people who consumed high-fat meals. On the other hand, post-meal exercise appeared to reduce blood glucose levels but not triglyceride levels in both healthy and diabetic patients. As little as 20 minutes of post-meal aerobic exercise may help keep your blood sugar under control and prevent type 2 diabetes.
Researchers in Washington, DC, found that post-meal exercise had the greatest effect on blood glucose levels. Ten inactive, nonsmoking older (> 60 years) men and women at risk for impaired glucose tolerance (but otherwise healthy) formed the study cohort. Each participant performed three moderate-intensity treadmill exercise protocols in random order: 1) 15 minutes of exercise at 30 minutes following breakfast, lunch, and dinner, 2) 45 minutes of exercise at 10:30 am, and 3) 45 minutes of exercise at 4:30 pm. Researchers found that walking thrice daily for 15 minutes each was equally effective as one 45-minute exercise period in improving glucose levels over 24-hour hours. Post-meal exercise significantly controlled blood glucose for 3 hours, while the other exercise protocols did not. Blood glucose over 24 hours strongly correlated with blood glucose over 3 hours. Thus, an after dinner walk might have the greatest relative benefit for overall daily glucose control. Three short bouts of exercise may be more palatable for busy people than a longer period, thus increasing the probability that more people would walk for 15 minutes after each meal. Three daily 15-minute post-meal walks would also help reach 10,000 daily steps.
Physician Elsamma Chacko provided a first-had account of her 16-year journey with type 2 diabetes. To manage her diabetes, she combined pre-meal exercise while controlling her carbohydrate intake. She lost 14 percent of her body weight in four months, but her HbA1c readings didn’t change. HbA1c is a protein whose concentration denotes average blood sugar concentration over the preceding 2-3 months. Her stable HbA1c levels indicated that her blood sugar levels didn’t change, in spite of losing weight. Then she switched to post-meal exercise consisting of walking starting 30 minutes after she finished eating and continuing for up to one hour. Thirty minutes corresponds to the time that blood sugar starts rising after a meal. Over four months, she again lost 14 percent of her body weight and reduced her HbA1c from 7.2 to 6.0 percent. This decline is clinically meaningful and suggests well-controlled type 2 diabetes. HbA1c levels below 4.7 percent indicate no diabetes.
As of 2016, official advice encouraged diabetics to walk to manage their blood sugar. A recent randomized, controlled trial showed that the advice should be revised to encourage after-meal walking. Researchers fitted 41 type 2 diabetic participants (average age 60 years) with continuous glucose monitoring systems for two weeks. Half of the participants walked for 10 minutes starting 5 minutes after completing each of their three daily meals. The other half walked 30 minutes in one occasion each day. After two weeks of glucose monitoring plus an additional two-week washout period, the participants switched their walking routines for two weeks. Researchers found that three daily bouts of 10-minute post-meal walking lowered glucose 12 percent more than a single bout of walking for 30 minutes performed at any time during the day. After-dinner walking made the greatest contribution to glucose lowering. This effect likely reflected the prevalence of carbohydrate-rich dinners.
A new study by British researchers investigated whether physical activity that occurred immediately before or after breakfast or later in the day most affected post-meal glucose concentration. Forty-eight generally healthy, physically active adults were randomly assigned to one of three physical activity conditions: standing, walking, and circuit training, each for 30 minutes. Within each activity condition, participants completed four trials in random order. Compared to the participants in Trial A (physical activity later in the day), participants in Trial C (immediate post-meal activity) had significantly lower average glucose and lower area under the glucose curve (that is, lower average glucose over 2 hours post-meal) regardless of the type of physical activity. Thus, 30 minutes of light- to moderate-intensity physical activity immediately following breakfast most reduced the post-meal glucose spike and reduced glucose for 2 hours. After you finish each daily meal, can you find a way to move around for 10 minutes? Or maybe just 30 minutes following your biggest meal? If so, you’ll likely keep your blood sugar under control and greatly reduce your risk of type 2 diabetes.