A 70-year-old man with a history of type 2 diabetes takes insulin glargine (Lantus) 100 units every morning (he is afraid of developing hypoglycemia at night) and insulin aspart (Novolog) 20 units with each meal. However his blood sugar is still around 250 mg/dL. Can the Lantus dose be increased, and if so, to what? Or should the patient be switched to insulin detemir (Levemir) twice daily? Can the dose of Levemir be greater than 100 units? What else would you suggest for this patient?
—Mostafa M. Rehab, MD, Greensburg, Ind.
If your patient’s blood sugars are in the 250 range all day, he likely needs more insulin. Patients with type 2 diabetes will routinely need 1-2+ units/kg body weight per day. If he is requiring more than this, one should look for factors that might increase insulin resistance (infection, Cushing syndrome, etc.), noncompliance, or incorrect administration. (I have discovered that some patients who were supposed to be taking multiple shots of insulin per day were injecting air and not insulin!). There is no maximum dose of glargine per se, although at doses >100 units, I usually prescribe this agent b.i.d. In addition, we are finding that in some patients, Lantus seems to last only 12-18 hours, so that splitting the dose to 80 units in the morning and 30 units at bedtime would likely improve his morning/fasting blood sugars. Using insulin detemir b.i.d. at this dose would also suffice. Most patients on stable insulin regimens are taking approximately 50% as basal (glargine in this case) and 50% as bolus (mealtime aspart), so this patient likely needs an increase in his prandial doses. If, despite dosing adjustments that put him at 250-300+ units/day of insulin U-100, he is still not at goal, many diabetes specialists would consider U-500 insulin. With this last option, make sure that both the patient and pharmacist know that this is a concentrated form of insulin and that the doses (usually a fixed dose t.i.d. with meals) are clear to all involved in their administration. If this patient’s blood sugar levels are still not at goal despite using U-100 insulin 250 units total per day, I might try switching to U-500 20 units at each meal.
—Lyle D. Mitzner, MD, instructor in medicine, Harvard Medical School, Boston (127-1)
