DIABETES MELLITUS, TYPE 1   67A

A 22-year-old woman with a history of poorly controlled type 1 diabetes mellitus presents to the emergency department with abdominal pain, nausea, and vomiting. She had been feeling ill with a cough, sore throat, and decreased appetite, so she has skipped several doses of insulin. On physical examination, she is tachypneic, and her abdomen is diffusely tender to palpation without rebound or guarding. Serum testing reveals a glucose level of 512 mg/dL and an anion gap of 23, and her arterial pH is 7.12. Her urine dipstick is positive for ketones as well as glucose. A serum β-hydroxybutyric acid level is elevated.

What are the salient features of this patient’s problem? How do you think through her problem?

Salient features: Young age; abdominal pain, nausea, vomiting; recent illness and insulin nonadherence; anion-gap metabolic acidosis with resulting tachypnea; elevated serum and urine glucose; urine and serum ketosis

How to think through: What clinical evidence helps distinguish between type 1 and type 2 diabetes at the time of initial diagnosis? (Weight loss rather than obesity; absence of acanthosis nigricans, dyslipidemia, hypertension, or polycystic ovaries. Onset of type 1 is typically in early childhood or early puberty. Autoantibody tests positive.) With what symptoms did this patient most likely present at the time of diagnosis? (Polyuria, polydipsia, lethargy, and weight loss.) She now presents with the defining features of diabetic ketoacidosis (DKA). In DKA, it is crucial to identify the precipitating factor. What likely precipitated DKA in this case? (Cough and pharyngitis suggest she has an infection along with nonadherence to insulin.) Is any additional testing warranted to establish the precipitating factor? (Chest radiography, if history or examination suggests pneumonia, urinalysis, and in older patients, consider electrocardiography.) DKA is best managed using a protocol. What are the key clinical and laboratory factors to monitor? (Volume status, serum glucose, bicarbonate, anion gap, potassium, and corrected sodium.) How much volume repletion is typically needed in DKA? (4–6 L.)

DIABETES MELLITUS, TYPE 1   67B

What are the essentials of diagnosis and general considerations regarding type 1 diabetes mellitus?

Essentials of Diagnosis

Polyuria, polydipsia, and weight loss associated with random plasma glucose ≥200 mg/dL

Plasma glucose ≥126 mg/dL after an overnight fast documented on more than one occasion

Ketonemia, ketonuria, or both

General Considerations

Caused by pancreatic islet β-cell destruction, usually immune-mediated

Most type 1 patients possess either HLA-DR3 or HLA-DR4; HLA-DQB1*0302 is very specific

Most patients have circulating antibodies to islet cells (ICA), insulin (IAA), glutamic acid decarboxylase (GAD65), and tyrosine phosphatase IA2 (ICA-512) and zinc transporter 8 (ZnT8) at diagnosis

Prone to ketoacidosis

Occurs at any age but most commonly arises in children and young adults

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