A 7-year-old girl presents with increased thirst and urination over the last 2 weeks. Despite previously being dry at night, she has wet the bed a few times over the past week. She has not been ill and has had a good appetite. She has had no abdominal pain or vomiting. Physical examination is remarkable for dry, tacky oral mucous membranes. Her weight is down 3 kg since her last well-child visit. A blood sugar is checked (Figure 189-1) on a meter and is “high” or too elevated to be read by the meter. A urinalysis shows positive glucose and ketones in his urine. A basic metabolic profile reveals sodium of 131 mEq/L, bicarbonate of 20 mEq/L, and plasma glucose of 652 mg/dL. Hemoglobin A1c is 10.8 percent. She is admitted to the hospital with the diagnosis of new onset diabetes. She is treated with intravenous fluids and insulin. While in the hospital, she is started on SQ insulin injections and she and her family receive diabetes education. With her age, the patient most likely has type 1 diabetes mellitus (T1DM).

The classic symptoms of new onset diabetes are polydipsia, polyuria, and unexpected weight loss.

T1DM has also been called insulin-dependent diabetes, juvenile-onset diabetes, and immune-mediated diabetes.

• 
  

  The incidence of T1DM is increasing by about 3 percent per year for unknown reasons.

  
  
• 
  

  Less common forms of diabetes in children and adolescents include type 2 diabetes (T2DM), cystic fibrosis related diabetes (CFRD), steroid-induced diabetes, and rare genetic forms of diabetes.¹

  
  
• 
  

  The prevalence of T1DM in the US at 18 years of age is about 2 to 3 per 1,000 individuals.²

  
  
• 
  

  Males and females are equally affected.

  
  
• 
  

  There are two peaks in incidence of T1DM in children: as they start school (4 to 6 years) and early adolescence (10 to 14 years).

  
  
• 
  

  The incidence of T2DM has also increased associated with the rise in childhood obesity. T2DM most often occurs in pubertal adolescents.

• 
  

  T1DM is due to autoimmune beta cell destruction in the pancreas resulting in absolute insulin deficiency.

  
  
• 
  

  T2DM is due to insulin resistance and relative insulin deficiency.

• 
  

  There is an increased risk of developing T1DM if there is an already affected relative: 6 percent risk in a sibling; <50 percent chance in an identical twin; higher risk if the father has T1DM compared to a mother with T1DM.²

  
  
• 
  

  Obesity, positive family history, ethnic minority, and evidence of insulin resistance are common risk factors for T2DM.

Clinical Features

• 
  

  Polyuria, polydipsia, polyphagia, and weight loss are the classic features of new onset diabetes.

  
  
• 
  

  When presenting in diabetic ketoacidosis (DKA), additional features include nausea, vomiting, abdominal pain, mental status changes, and Kussmaul breathing.

  
  
• 
  

  Acanthosis nigricans on the neck, axilla, or other skin folds is a sign of insulin resistance seen in T2DM and obese individuals (Figure 189-2; see Chapter 190, Acanthosis Nigricans). Genetic defects in insulin action can result in extreme insulin resistance (Figure 189-3).

  
  
• 
  

  Necrobiosis lipoidica diabeticorum (NLD) is a rare skin condition occurring in <0.5 percent of diabetics and seldom seen in children (Figure 189-4).