Type 1 Diabetes Mellitus in Children and Adolescents: Part 1, Overview and Diagnosis

Type 1 Diabetes Mellitus in Children and Adolescents: Part 1, Overview and Diagnosis

Case: A 15-month-old boy is brought to his family practitioner’s office for evaluation of severe candidiasis in his diaper region that has been present for the past 2 weeks. His mother has used over-the-counter barrier creams, but the condition has not resolved. In addition to her concern about the rash, the mother also notes that he has been irritable with his voids, and she thinks he may have dysuria. Questioning reveals a 1-week history of increased wet diapers at night that soak the bed, increased thirst, weight loss, and decreased energy. The child is otherwise healthy; he has no history of medical problems and currently takes no medications. What investigations should be included in the workup?

Type 1 diabetes mellitus (T1DM) is the most common endocrine problem seen in children and adolescents. T1DM is the result of immune-mediated destruction of pancreatic cells; it involves the formation of autoantibodies against insulin and various enzymes and results in an inability to produce insulin.1 Type 2 diabetes mellitus (T2DM), in contrast, is associated with insulin resistance and obesity.2 T1DM is more common in children than T2DM, although the incidence of T2DM in children is currently increasing in association with the increase in childhood obesity.3 Family physicians and general pediatricians are often responsible for making the initial diagnosis of T1DM in children and then for treating the disease in these patients. In this article, we review the epidemiology and diagnosis of pediatric T1DM. In Part 2 of this article (on page 69 of this issue), we will focus on the management of T1DM in children and adolescents.

The incidence of T1DM in children varies widely. It is higher in Caucasian populations and in populations at a distance from the equator.4 For the years 1990 to 1994, the countries that had the highest incidence rates of T1DM in children 14 years or younger were Finland, with 36.5 per 100,000 per year; Sweden, with 27.5 per 100,000 per year; Canada (Prince Edward Island), with 24.5 per 100,000 per year; and Norway (8 counties), with 21.2 per 100,000 per year.4 China and South America had the lowest incidence rates: less than 1 per 100,000 per year.4 In the United States, the incidence rate has been reported as between 11.7 and 17.8 per 100,000 per year.4

There is evidence that in younger populations the incidence of T1DM may be increasing. In a study of children younger than 15 years, the overall incidence of T1DM from 1990 to 1999 was found to have increased by 3.6% per year in peninsular Italy and by 3.7% per year in Sardegna.5 In the Avalon Peninsula of Newfoundland, Canada, the incidence of T1DM was found to have increased at a rate of 1.25 per 100,000 per year from 1987 to 2002.6

Interestingly, in a Swedish study of persons from a wider age-range (0 to 34 years), covering the period from 1983 to 1998, there was no overall increase in T1DM incidence but rather a shift to a younger age at diagnosis.7 The incidence of T1DM increased over time in children younger than 14 years but decreased in persons in older age-groups.7 This may suggest that the disease develops earlier in persons at risk than it did in the past. It is unclear at the present time what specific factors are responsible for the increase in incidence of T1DM in younger patients. Genetic factors or environmental factors—such as pollution, viruses, toxins, or lifestyle habits—may be responsible.1,8,9


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