A 32-year-old male presents with a 1-year history of increasing fatigue, polyuria, and a gradual 30-lb weight loss. Serum chemistries reveal a bicarbonate level of 23 mEq/L (N 22–28), a corrected anion gap of 8 mEq/L (N 3–11), and a glucose level of 658 mg/dL (N 60–110). The patient is admitted to the hospital and his serum glucose drops to 174 mg/dL after he is given 2 L of intravenous normal saline and 10 units of regular insulin subcutaneously. He is observed overnight and further laboratory testing is done the next morning.
Which one of the following is more consistent with type 2 diabetes mellitus than with type 1 diabetes mellitus? Ans: The time course of symptom onset
This patient presents with marked hyperglycemia but no evidence of ketoacidosis or nonketotic coma. Differentiating between type 1 and type 2 diabetes mellitus is important for guiding therapy. The gradual onset of symptoms is more consistent with type 2 diabetes mellitus, whereas type 1 diabetes typically has a more rapid onset. Patients with type 1 diabetes typically need lower doses of insulin to correct hyperglycemia, as they lack the insulin insensitivity that is the hallmark of type 2 diabetes. Positive anti-GAD antibodies and low C-peptide at the time of the initial diagnosis are also consistent with type 1 diabetes, although C-peptide levels can also be low in long-standing type 2 diabetes. Weight loss occurs in both types of diabetes mellitus when glucose is profoundly elevated.
Ref: Goldman L, Schafer AI (eds): Goldman’s Cecil Medicine, ed 24. Elsevier Saunders, 2011, pp 236, 1475-1489.