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.
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