It took me about 12 months to come to terms with diabetes. It was very frustrating. You want your body to do what you tell it to do.
Sir Stephen Redgrave, English rower who won his fifth Olympic gold medal in 2000, three years after being diagnosed with diabetes
In this chapter we examine two aspects of the relationship between diabetes mellitus and exercise:
British rower Sir Steven Redgrave (chapter opening quote) provides a remarkable story of sporting success despite having diabetes mellitus.1 Many other athletes with diabetes have also been extremely successful: Jay Cutler, a National Football League (NFL) quarterback who was diagnosed with type I diabetes in 2008, continued his successful playing career.
There are two distinct types of diabetes mellitus—type 1 and type 2.
Type 1 diabetes, previously known as “juvenile-onset diabetes,” is thought to be an inherited autoimmune disease in which antibodies are produced against the beta cells of the pancreas. This ultimately results in the absence of endogenous insulin production, which is the characteristic feature of type 1 diabetes.
The incidence of type 1 diabetes varies throughout the world but represents approximately 10–15% of diabetic cases in the Western world.
The onset commonly occurs in childhood and adolescence but can become symptomatic at any age. Insulin administration is essential to prevent ketosis, coma, and death. The aims of treatment are tight control of blood glucose levels and prevention of microvascular and macrovascular complications.
Type 2 diabetes, previously known as “maturity-onset” or “adult-onset” diabetes, is a disease of later onset, linked to both genetic and lifestyle factors. It is characterized by diminished insulin secretion relative to serum glucose levels, in conjunction with peripheral insulin resistance, both of which result in chronic hyperglycemia.
Approximately 90% of individuals with diabetes have type 2 diabetes and it is thought to affect 3–7% of people in Western countries. The prevalence of type 2 diabetes increases with age. The pathogenesis of type 2 diabetes remains unknown but it is believed to be a heterogeneous disorder with a strong genetic factor. Approximately 80% of individuals with type 2 diabetes are obese.
Type 2 diabetes is characterized by three major metabolic abnormalities:
impairment in pancreatic beta cell insulin secretion in response to a glucose stimulus
reduced sensitivity to the action of insulin in major organ systems such as muscle, liver, and adipose tissue
excessive hepatic glucose production in the basal state.