Building Competency in Diabetes Education THE ESSENTIALS

3-34 | CHAPTER 3

EPIDEMIOLOGY

Diabetes affects people all over the world; however, some population segments are affected more than others. Both type 1 and type 2 diabetes show significant variation in incidence between highest- and lowest-risk countries.

Incidence The incidence (number of people who develop the disease per year) of both type 1 and type 2 is on the rise, likely due to a number of factors (25,33): • Environment: The incidence of diabetes in populations at low risk increases when members of those populations relocate to geographic areas where the incidence of diabetes is higher. Migration studies of genetically homogeneous groups have enabled the influence of environment to be examined. Among environmental factors that may be implicated are those that contribute to obesity. With the rise in obesity, comes an associated rise in the incidence of type 2 diabetes. • Geographic location: Diabetes is also increasing in various geographic locations. Type 1 is more prevalent in populations that live further from the equator. Significant differences in the prevalence of type 2 exist between different ethnic and racial groups, even within specific countries. • Age: The prevalence of type 2 diabetes shows dramatic increases with advancing age. The majority of cases are found among the elderly (i.e. >65 years). Type 1 diabetes may develop at any age, but it is rare in the first six months (47). • Genetic factors: The role of genetics in diabetes is different for type 1 and type 2. Human leukocyte antigen (HLA) genes influence the susceptibility to type 1 diabetes and it is a graded association as some loci carry higher risk than others (47). Although the genetic susceptibility in type 1 diabetes is established, only those predisposed will develop diabetes as evident in twin studies (47). Globally, 1,106,200 children and adolescents under the age of 20 are living with type 1 diabetes and about 132,600 will be diagnosed with type 1 diabetes each year (48). About 10-20% of newly diagnosed childhood cases of type 1 diabetes have an affected first-degree relative (47). The incidence of type 1 diabetes is rising at an alarming rate of 3% per year (48). Compared to Caucasians, the incidence of type 1 diabetes is lower in Indigenous peoples and those of African, Asian and Hispanic descent.