ABIM & Internal Medicine Shelf Exam Review Question of the Week: 32 y.o female with DM requiring Insulin follow up
32-year-old female presents to your office for symptoms of diabetes mellitus including polyuria. You check her random sugar level in the office and it comes back at 205mg/dL. You diagnose her with diabetes mellitus. In the clinic, you order a HgbA1c and it comes back at 11.5%. She weighs 60kg so based on her weight, you start her on 15 units of glargine and 5 units of lispro with each meal. She comes back a few months later and shows you an average of her pre-meal and post-meal sugars.
Breakfast: Pre-meal [110mg/dL], Post-Meal [185mg/dL]
Lunch: Pre-meal [104mg/dL], Post-Meal [190mg/dL]
Dinner: Pre-meal [108mg/dL], Post-Meal [192mg/dL]
Which of the following is the next best step in management?
A. Increase glargine; increase lispro for breakfast, lunch and dinner B. Decrease glargine; no change in lispro for breakfast, lunch and dinner C. Increase glargine; no change in lispro for breakfast, lunch, and dinner D. No change in glargine; increase lispro for breakfast, lunch, and dinner E. No change in glargine and no change in lispro for breakfast, lunch and dinner
ABIM Exam Question Explanation
Glargine is a long-acting insulin. Lispro is an example of a short-acting insulin that is used with meal-time coverage. A random blood sugar of greater than 200mg/dL is one way of diagnosing diabetes mellitus. Since this patient has a high HgbA1c, it would be wise to start her on an insulin regimen. Usual insulin regimen is 0.5units/kg with half being as glargine (long-acting insulin) and half as short-acting insulin. You then divide the short-acting insulin into the three meals.
This patient weighs 60kg which translates to 30 units of insulin when 0.5 units/kg is used. Therefore, 15 units of insulin was given as glargine and 5 units with each meal of lispro for the other 15 units of insulin. ADA guidelines recommend that HgbA1c should be less than 7%, pre-prandial glucose should be around 90-130mg/dL, and post-prandial glucose should be less than 180mg/dL. If the pre-prandial sugars are high, then the long-acting insulin regimen needs to be increased. If the post-prandial glucose is high, the short-acting insulin needs to be increased.
From the above example, we see that the pre-meal sugars are all between 90-130mg/dL which indicates that the glargine does not need to be changed. The post-meal sugars, however, are not at the goal of below 180mg/dL. Therefore, we must increase the short acting insulin at breakfast, lunch and dinner.
Putting all these points together makes Choice D (No change in glargine; increase lispro for breakfast, lunch, and dinner) the correct answer.
You can view all the previous ABIM Exam Review Questions of the Week at the Knowmedge Blog. You can also find additional topics and questions directly from the Knowmedge Internal Medicine ABIM Board Exam Review Questions QVault.
