Test Your Knowledge Answer #483

(Correct Answer = D)

This patient's glycemic control is clearly suboptimal on his current treatment with glyburide and metformin; in fact, the latter drug is now contraindicated because the patient's serum creatinine concentration has exceeded 1.5 mg/dL (132.63 µmol/L) (1.4 mg/dL [123.79 µmol/L] in women). The most appropriate approach is to stop the metformin and glyburide and start insulin treatment. In this case, starting a premixed insulin such as 70% neutral protamine aspart–30% insulin aspart twice daily before breakfast and dinner is appropriate because his carbohydrate intake is consistent and his glucose pattern shows quite a narrow range of glucose levels without wide swings.

Continuing metformin and glyburide while adding basal insulin to his treatment or adding a premixed insulin before dinner and continuing his oral anti-diabetes medications would not be appropriate for the reasons listed above. In addition, substituting rosiglitazone for metformin is not likely to further lower the hemoglobin A1C value; if the patient were able to continue metformin, the addition of rosiglitazone would lower the A1C value by no more than 1.5 percentage points, which would not achieve the target of less than 7%.

1. Yale JF, Valiquett TR, Ghazzi MN, Owens-Grillo JK, Whitcomb RW, Foyt HL. The effect of a thiazolidinedione drug, troglitazone, on glycemia in patients with type 2 diabetes mellitus poorly controlled with sulfonylurea and metformin. A multicenter, randomized, double-blind, placebo-controlled trial. Ann Intern Med. 2001;134:737-45. [PMID: 11329231] [PubMed]