This is the second in a two article series on Diabetes and Exercise. This article will discuss type 2 diabetes and how to manage blood sugars during and after exercise. A number of key ideas regarding the fundamentals of fuel metabolism in conjunction with exercise were discussed in the first article in the last issue (Fall Equinox, Vol. 4, No.2 ) and I recommend you review that information since it is relevant to this article.

Type 2 diabetes is typically the result of the following breakdowns in glucose regulation :

• increased insulin resistance in the body tissues
• decreased insulin output by the pancreas
• excessive glucose output by the liver.

Typically these breakdowns occur gradually over the course of years. It is worth noting that this is different from type 1 diabetes where the primary problem is the almost complete absence of insulin production by the pancreas with the breakdown being immediately apparent as symptoms can be life threatening. The treatment for type 1 diabetes is relatively simple and the choices few; insulin. In some way some type of insulin will be delivered into the body as treatment. It may be a pen, a syringe, a pump or eventually inhaled but the same principal applies; the provision of insulin that the body's pancreas no longer makes. With type 2 diabetes the options are varied and will likely change over time as the disease progresses. Insulin resistance, insulin production and excessive liver glucose production will all change over time and require adjustments in therapy. I emphasize this point since, as you will read later, the nature of the diabetes therapy will determine the degree of risk of low blood sugars and the necessary precautions to take before exercising.

Benefits Of Exercise

There are numerous benefits of a regular exercise program and they are listed in Table 1. I will highlight a few of my favorites here. One of the immediate benefits, besides having fun and feeling good, is the reduction in blood sugar. In addition there is the potential for improved cardiovascular fitness. I think one of the greatest benefits, however, is the potential to reverse the underlying mechanism of insulin resistance that can lead to diabetes in the first place. Exercise tends to reduce this resistance and increase insulin sensitivity enabling the body to regulate blood glucose (BG) levels more effectively.

Table 1. Benefits of exercise for patients with Type 2 Diabetes Lower blood glucose concentration during and after exercise Lower basal and postprandial insulin concentrations Improved insulin sensitivity Lower HbA1c levels Improved lipid profile Decreased triglycerides Slightly decreased low-density lipoprotein (LDL) (bad fat) Increased high-density lipoprotein (HDL) (good fat) Improvement in mild to moderate hypertension Increased energy expenditure Adjunct to diet for weight reduction Increased fat loss Preservation of lean body mass Cardiovascular conditioning Increased strength and flexibility Improved sense of well-being and enhanced quality of life

Risks of Exercise

The risks of exercise are listed in table 2. Yes it is a rather large list and for that reason it is highly recommended that you consult your physician and/or diabetes specialist before starting an exercise program. You can even present them with this list if you wish to be sure they are aware and can tell which risks apply to you. The most immediate risk for the majority of individuals will be hypoglycemia (low blood sugars), either during or after exercising. To better understand this risk we need to understand the approaches to type 2 diabetes therapy.

Table 2. Risks of exercise for patients with Type 2 Diabetes Hypoglycemia if treated with insulin or insulin secretegogues (eg. glyburide, amaryl, gluconorm) Exercise-induced hypoglycemia Late-onset post exercise hypoglycemia Hyperglycemia after very strenuous exercise Precipitation or exacerbation of cardiovascular disease Angina pectoris Myocardial infarction Arrhythmias Sudden death Worsening of long-term complications of diabetes Proliferative retinopathy Vitreous hemorrhage Retinal detachment Nephropathy Increased proteinuria Peripheral neuropathy Soft tissue and joint injuries Autonomic neuropathy Decreased cardiovascular response to exercise Decreased maximum aerobic capacity Impaired response to hydration Postural hypertension Altered gastrointestinal function