Epidemiology and Disease Pathology of Pediatric Diabetes

According to data from the Centers for Disease Control, the prevalence of diagnosed diabetes in people under 20 years old in the US is approximately 210,000, which represents 0.26% of all people in this age group.[1] For type 1 diabetes, 1 in every 400 to 500 children and adolescents has the disease, making it one of the most common chronic diseases in children in the US.[1] Prevalence varies with ethnic group, type of diabetes, and geographical location, and ranges from 50.9 cases of type 2 diabetes per 1000 among Pima Indians in Arizona to an average of 1.7 cases of type 1 diabetes per 1000 in the general US population aged 0 to 19 yrs.[2]

Type 2 diabetes in children has been rising disproportionately for the past decade, especially in some geographical areas in the US such as Ohio and Arkansas, where as many as 75% of newly diagnosed cases of pediatric diabetes have type 2 diabetes.[3]

The forms of diabetes seen in children and youths include the following:

Type 1 diabetes

• Autoimmune

  • Typical type 1 diabetes, which occurs across all races (the majority of cases) and results from β-cell destruction

  • Idiopathic

  • Atypical type 1 diabetes (rare)

Type 2 diabetes

• Nonautoimmune

  • Predominantly seen in minority youth; largely inherited; related to obesity and low birth weight

  • Ranges from a condition predominantly characterized by insulin resistance with relative insulin deficiency to a condition that is predominantly a secretory defect with insulin resistance

Other types of diabetes

• Youth-onset atypical diabetes (YOAD)--a genetic disorder in African American populations

• Maturity-onset diabetes of the young (MODY)--seen rarely and only in whites (an inherited β-cell defect)

• Diabetes from other causes

  • Defect in insulin action

  • Defect in exocrine pancreas (eg, cystic fibrosis)

  • Endocrinopathy (eg, Cushing’s syndrome)

  • Drug- or chemical-induced endocrine abnormality (eg, glucocorticoids; growth hormones)

  • Infectious disease (eg, rubella)

  • Uncommon forms of immune-mediated diabetes

  • Other genetic syndromes (eg, Prader-Willli syndrome)[4-7]

Type 1 diabetes

Epidemiology

Type 1 diabetes is the most common metabolic illness affecting children, with a yearly worldwide incidence of 82,000 cases in those under 14 years of age.[8] The occurrence of type 1 diabetes is increasing in all populations at a rate of approximately 3% per year.[9] Type 1 diabetes also is presenting at an earlier age, with large increases in children aged 0 to 4 years.[9]

Associated with a 2- to-10-fold excess risk of mortality prior to age 40, type 1 diabetes can lead to early mortality because of short-term complications (notably diabetic ketoacidosis) or long-term complications.[9] Onset of type 1 diabetes peaks in the early adolescent years (ages 11 to 13); this is coincident with prepuberty or puberty.[10]

Disease pathology

There are many theories for the causes of type 1 diabetes, including pancreatic β-cell destruction from viral infections and environmental factors (toxic chemicals, exposure to the protein in cow's milk in infancy, cytotoxins).[10] Lifestyle factors may play a role, and may help in understanding more about the disease pathology of type 1 diabetes.

Much of the variation in susceptibility to diabetes is genetic rather than environmental; however, only 12% to 15% of type 1 diabetes occurs in families. The majority of cases of type 1 diabetes in children occur sporadically, rather than being clustered in families.[9] Only about 5% of children with type 1 diabetes have a first- or second-degree relative with the same disease.[6]

Type 2 diabetes

Epidemiology

Of the nonautoimmune forms of diabetes seen in youth, only type 2 diabetes is increasing in incidence.[4] Its increase in recent years has been observed mainly in African Americans, Native Americans, Mexican Americans, and Asian Americans.[3] Among nonwhite populations, type 2 diabetes now comprises 30% of new cases of diabetes in the second decade of life.[4] In Japan, type 2 diabetes is 7 times more common in school children than type 1, and its incidence there has increased more than 30-fold over the past 20 years.[4]

Prevalence of type 2 diabetes may be underestimated because it can be undiagnosed for long periods. Therefore, type 2 diabetes is no doubt more of a health dilemma than the prevalence numbers reveal. Even if a blood test is taken, criteria differentiating types of pediatric diabetes in children are so complex and confusing that many cases of type 2 diabetes may be recorded inaccurately as type 1 diabetes.[2]

Disease pathology

Type 2 diabetes is associated with obesity (particularly central, visceral fat)[6] with β-cell malfunction, and with insulin resistance.[3,4] The epidemic of obesity, exposure to diabetes in utero, and the low level of physical activity among young people may be major contributors to the epidemic of type 2 diabetes in children and adolescents.[5]

There is an emerging risk profile for type 2 diabetes, including the following:

• Relatives with the disease. Of children with type 2, 45% to 80% have a parent with diabetes and 74% to 90% have first- or second-degree relatives with diabetes.[3]
• Lifestyle changes leading to increased body weight (sedentary habits;diet).[5]
• Low birthweight. Infants born to mothers with gestational diabetes or poor nutrition/exercise, especially when combined with the child’s rapid gain in weight after birth and then being overweight just before puberty, are at increased risk.[5]
• Acanthosis nigricans, hyperglycemiation of the skin at the neck and elsewhere, is seen in up to 90% of cases and occurs due to insulin resistance.[3]
• Comorbidity with polycystic ovary disease, hypertension, and lipid disorders. [5]
• Puberty and female sex.[3]

Conclusion

The steady rise of type 1 diabetes among children and the emerging epidemic of type 2 diabetes in the pediatric population presents a serious public health problem now and for the future. Investigation to determine causes and obtain incidence and prevalence rates among large populations of children deserves high priority. Increased education and vigilance are needed in the healthcare community to address this serious concern.[4]

References

1. United States Department of Health and Human Services/Centers for Disease Control: CDC. National Diabetes Fact Sheet. National Estimates on Diabetes. Available at: http://www.cdc.gov/diabetes/pubs/estimates.htm#prev2. Accessed January 24,2006.
2. United States Department of Health and Human Services/Centers for Disease Control:CDC. Diabetes Projects. Available at: http://www.cdc.gov/diabetes/projects/cda2.htm. Accessed August 24, 2004.
3. Kaufman FR. Type 2 diabetes in children and young adults: a “new epidemic.” Clin Diabetes. 2002;20:217-218.
4. Rosenbloom AL, Joe JR, Young RS, Winter WE. Emerging epidemic of type 2 diabetes in youth. Diabetes Care.1999;22:345-354.
5. Bloomgarden ZT. Type 2 diabetes in the young: the evolving epidemic. Diabetes Care. 2004;27:998-1010.
6. American Diabetes Association Consensus Statement. Type 2 diabetes in children and adolescents. Diabetes Care. 2000;23:381-389.
7. American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2004;27:S5-S10.
8. international Diabetes Federation. Prevalence: types 1 and 2 diabetes. Available at: http://www.idf.org/e-atlas/home/index.cfm?node=53. Accessed August 28, 2004.
9. Karvonen M, Tuomilehto J, Podar T. Epidemiology of type 1 diabetes. In: Pickup JE, Williams G, eds. Textbook of diabetes, vol 1, 3rd edition. 2003.
10. Hussain AN, Vincent MT. Diabetes Mellitus, Type 1. Published by Emedicine (last updated March 2004). Available at: http://www.emedicine.com/med/topic546.htm. Accessed August 2004.