that impedes achievement of optimal glycemic control, new research suggests.
Such ‘overbasalization,’ defined as a hemoglobin A1c of greater than 8% despite use of more than 0.5 units/kg per day of basal insulin, was identified in about 40% of patients seen in a Florida primary care clinic during 2015-2018. The findings were published in the April 2021 issue of Clinical Diabetes by Kevin Cowart, PharmD, a diabetes care and education specialist at the University of South Florida, Tampa, and colleagues.
The literature suggests that once people with type 2 diabetes start basal insulin, the chance that they’ll achieve a given hemoglobin A1c target, i.e., less than 7%, diminishes significantly if that goal isn’t achieved within the first year of starting insulin, Dr. Cowart said in an interview.
“Our analysis suggests that overbasalization plays a role in patients with type 2 diabetes on basal insulin not achieving optimal glycemic control. Basal insulin is not designed to address postprandial hyperglycemia. I think there’s a clear need to address hesitancy in therapeutic progression beyond basal insulin. A lot of factors underlie the delays, with therapeutic inertia being one of them. It’s complex,” he said.
Overbasalization seen in large proportion of patients
The study comprised 655 adults diagnosed with type 2 diabetes for at least a year who received a prescription for a basal insulin (glargine U-100, glargine U-300, detemir, degludec U-100, degludec U-200, regular U-500, or NPH insulin).
The patients had a mean hemoglobin A1c of 8.4% and a mean basal insulin dose 0.4 units/kg per day. The prevalence of overbasalization was 38.1% for those with hemoglobin A1c above 8%, 42.7% for those with A1c of 9% or above, and 42% with A1c of 10% or greater.
Patient characteristics independently associated with overbasalization were age 35-54 years (odds ratio 1.89), age 65-80 years (0.44), A1c 9% or greater (13.97), and A1c 10% or greater (6.04). Having a prescription for insulin glargine U-100 was associated with a lower overbasalization risk (0.62). In multivariate analysis, only an A1c of 9% or greater remained significant.
Rozalina G. McCoy, MD, an endocrinologist and primary care clinician at the Mayo Clinic, Rochester, Minn., said in an interview that she sees [overbasalization] frequently in patients who are referred to her. “It’s kind of that wall that patients with type 2 diabetes hit because their A1c is high but their fasting blood sugars are normal. Sometimes it’s assumed that there’s a discrepancy, because people don’t always think about postprandial hyperglycemia.”
She also noted that there has been a push in recent years to simplify regimens, particularly in older patients.
“We really want to avoid rapid-acting insulin in older patients because we’re afraid of hypoglycemia, so we start them on basal and keep the noninsulins like metformin and sulfonylureas around. Initially those control the postprandial blood sugar but over time they’re no longer enough.”