ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Polyuria (heavy diapers in infants), polydipsia, weight loss, candidal infections.
Hyperglycemia and glucosuria, often with dehydration and ketonemia/ketonuria at presentation.
Diabetic ketoacidosis (DKA) can present as respiratory distress and/or severe nausea and vomiting.
Epidemiology & Description
Diabetes mellitus is defined by chronic hyperglycemia caused by defects in insulin secretion, insulin action, or a combination of the two.
Type 1 diabetes (T1D) is characterized primarily by insulin deficiency and is the most common type of diabetes mellitus in people younger than 20 years. It can develop at any age and most cases are diagnosed after age 20. The classical presentation includes increased thirst (polydipsia), increased urination (polyuria), and weight loss; however, the patient may be overweight or even obese. T1D is further divided into T1a (autoimmune) (~ 95% of the cases) and T1b (idiopathic) diabetes. T1b is more common in individuals of African or Asian ancestry. In the United States, T1D affects an estimated 1.6 million people, including about 190,000 patients younger than 20 (~ 18,000 diagnosed annually).
T1D incidence is the highest in children of European ancestry, followed by people of African American and Hispanic ancestry; rates are low in Asians and Native Americans. About 6% of siblings or offspring of persons with T1D also develop diabetes (compared with prevalence in the general population of 0.2%–0.3%). However, fewer than 10% of children newly diagnosed with T1D have a parent or sibling with the disease.
Type 2 diabetes (T2D) is characterized by resistance to the action of insulin. Insulin production may be high initially, but it gradually decreases leading to hyperglycemia.T2D has a heterogeneous phenotype and is diagnosed most often in persons older than 40 who are usually obese and initially not insulin dependent. T2D is rare before age 10; however, puberty is a time of heightened risk for development of T2D in susceptible individuals. Due to increased prevalence of childhood obesity, T2D has increased in frequency in older children. T2D is more common in youth of ethnic and racial minorities, particularly the Native American population. Other risk factors include female sex, poor diet and sleep, and low socioeconomic status. The vast majority of the 34 million patients with diabetes in the United States have T2D, but only about 20,000 patients are younger than 20 (~ 5800 diagnosed annually).
C. Monogenic Forms of Diabetes
Monogenic forms of diabetes can be diagnosed at any age and are caused by single gene defects affecting insulin signaling and secretion. The two major categories of monogenic diabetes are maturity-onset diabetes of the young (MODY) and neonatal diabetes. They account for 1%–2% of childhood diabetes, but form the majority of cases diagnosed before the ninth month of life. ...