Exercise is not always a walk in the park for type 1 diabetics. Before participating in any strenuous physical activity, they need to balance the amount of insulin taken with the amount of carbohydrates consumed with the duration and type of exercise they plan to engage in to prevent wild swings in their blood glucose levels.
The Importance of Blood Glucose and Glycogen
Carbohydrates provide your body with glucose. In a healthy person, the pancreas responds to an increase of glucose in the bloodstream by secreting a hormone called insulin. The insulin helps to transport the glucose to the body's cells to provide them with the energy they need to survive. When the body has taken in as much energy as it needs, it stores excess glucose away as fat to help fuel the body when glucose is in short supply. The liver stores some of the glucose to produce glycogen, used to keep a consistent supply of glucose in the bloodstream between meals.
The Impact of Type 1 Diabetes
Usually diagnosed during childhood or early adolescence, type 1 diabetes is a chronic disease characterized by the inability of the pancreas to produce a sufficient supply of insulin. Type 1 diabetics must mimic the job of the pancreas by closely monitoring their blood glucose levels and injecting insulin to prevent the levels from spiking too high --- a condition called hyperglycemia --- and eating carbohydrates to keep them from dipping too low, called hypoglycemia. Normal blood glucose levels range from 70 mg/dl to 120 mg/dl.
How Exercise Influences Blood Glucose Levels
When you exercise, your muscles require more energy than normal. Your body starts to create additional glucose from stored fat, and the liver releases additional amounts of glycogen into the bloodstream. When you stop the physical activity, your body no longer requires the additional energy from the blood glucose and stops producing more of it from fat reserves and glycogen. Glucose starts to pile up in the bloodstream, often resulting in a temporary state of hyperglycemia. Insulin in your bloodstream works to counteract the rise in blood glucose. This lack of glucose production and insulin working in overdrive often results in a bout of hypoglycemia, or low blood glucose.
Preparing for Physical Activity
Several techniques exist to help regulate the body's glycemic response before, during and after exercising. Always start by testing your blood glucose levels. The American College of Sports Medicine cautions against participating in strenuous exercise if your blood glucose levels are greater than 300 mg/dl, or greater than 250 mg/dl with the presence of ketones in the urine. Consume carbohydrates as necessary to get your blood glucose levels above 100 mg/dl before starting any exercise routine. Consider the type and duration of exercise when determining how many carbohydrates and what types you should consume, and balance that with the amount of insulin taken during your last injection. A 15-minute walk will use up considerably less carbohydrates than a one-hour game of basketball. Be prepared with fast-acting carbohydrates, such as a sports drink or glucose tablets, if you plan to participate in strenuous exercise that lasts for more than one hour.
