At a follow-up appointment your 53-year-old African American patient reported polyruia and polydipsia; his A1C had risen over 3 months from 8.1% to 9.2%. You have discussed with him the need to consider adding insulin to his current treatment with metformin 1000 mg twice daily. He also is treated for hypertension and osteoarthritis and admits to unreliable adherence to his daily regemin of pills. He has an erratic daytime schedule as a retail store manager and is not as careful as he "should be" about eating breakfast and lunch or following his dietary guidelines.
After a discussion of the pros and cons of insulin therapy, the patient agrees to start.
Answer: D. Continue metformin, initiate insulin glargine 10 units QHS with self-titration to glucose goals
Basal insulin therapy dosed once daily at bedtime is the best choice for this patient. Basal insulin therapies such as glargine, detemir, and NPH insulin supplement remaining endogenous insulin production to help normalize fasting blood glucose levels and can also help preserve beta-cell function. The addition of low-dose basal insulin to oral antidiabetic drugs can result in a majority of patients achieving an A1C goal of <7% with minimal risk of hypoglycemia.
Most patients will require at least some titration of the basal insulin dose to reach target A1c. In willing and able patients, patient driven self-titration protocols have been shown to be more effective than clinic-controlled protocols. Two common self-titration methods are to instruct the patient to increase basal insulin by 1 unit on every day the fasting glucose is >100mg/dL or increase the dose by 2 units every 3 days until fasting levels are within goals.
While a basal-bolus insulin regimen (option A) can be ideal for some patients, this patient already has admitted poor adherence to multiple daily doses of medications. Basal-only regimens, titrated appropriately, will allow the majority of patients to achieve glycemic goals with just 1 injection daily. Addition of bolus, or prandial, insulin should be considered when an optimally titrated basal regimen fails to get the patient to goal or if post-prandial goals are not reached once fasting glucose levels are at goal.
A premixed insulin product (option B) could be considered for this patient based on the ability of these agents to lower A1C and treat symptoms of hyperglycemia; however, it is not the most appropriate choice for him for several reasons. This patient does not have a routine work schedule and often skips a meal. A premixed insulin regimen is most effective for persons who maintain a fairly regular daily routine, including regular meals taken at regular times. This patient’s lifestyle could place him at increased risk for hypoglycemia, especially if he skips lunch. If he progresses to the need for bolus therapy, pre-mixed insulin can be considered as this would decrease the total number of injections daily; however, the patient would need counseling on lifestyle habits to prevent hypoglycemia with this insulin regimen. Importantly, the patient is insured and therefore would likely not benefit from the decreased cost of Novolin 70/30 vs glargine.
In all patients without contraindications, metformin should not be discontinued when insulin is initiated (option C). Continuing metformin can improve glycemic control and outcomes, decrease the insulin dose required, and prevent additional weight gain without increasing the risk for hypoglycemia.
NPH insulin (option E), while an acceptable option is not the best option for this patient. Basal insulin analogues have proven to be just as effective as NPH while decreasing the occurrence of hypoglycemia, specifically nocturnal hypoglycemia. Also, this patient is insured and may not benefit from the decreased cost of NPH.