New-onset type 1 diabetes mellitus most commonly presents with which condition?

• A. Hyperosmolar hyperglycemic state
• B. Diabetic ketoacidosis
• C. Hypoglycemia without ketosis
• D. Cushing syndrome

Answer: (B)

New-onset type 1 diabetes most often presents with diabetic ketoacidosis. The underlying issue is an absolute lack of insulin from autoimmune destruction of beta cells, which triggers rapid lipolysis and ketogenesis. The result is high blood glucose with an anion-gap metabolic acidosis and dehydration, often with rapid breathing, abdominal pain, nausea, vomiting, and a fruity breath. Labs typically show hyperglycemia, metabolic acidosis with positive serum or urine ketones, and electrolyte disturbances including potassium shifts. Hyperosmolar hyperglycemic state tends to occur more with type 2 diabetes or in older patients and features extreme glucose elevations with little to no ketosis. Hypoglycemia without ketosis is not the typical initial presentation of new-onset type 1 diabetes and is more common after treatment begins. Cushing syndrome can cause hyperglycemia but is not the presenting pattern for new-onset type 1 diabetes.