Health Outcomes Associated with Insulin after OAD Therapies

San Diego—Despite clinical practice that usually does not include the introduction of insulin therapy in patients newly diagnosed with type 2 diabetes mellitus (T2DM), most patients will eventually require treatment with insulin to maintain good glycemic control.

Though American Diabetes Association guidelines recommend basal insulin as a second-line therapy following initial oral antidiabetic drug (OAD) treatment (such as metformin), there has been no examination of the clinical and economic benefits of early initiation of insulin therapy in the real-world setting.

The objective of a recent analysis was to investigate real-world clinical and economic outcomes associated with the initiation of basal insulin therapy in patients with T2DM who were originally treated with 1, 2, or >3 oral antidiabetic drugs (OADs). The researchers presented the results of their study during a poster session at the AMCP meeting. The poster was titled Diminishing Rate of Return? Health Outcomes Associated with Initiation of Basal Insulin after 1, 2, or 3+ Oral Antidiabetic Drugs among Managed-Care Patients with Type 2 Diabetes.

This retrospective, observational study used data from the IMPACT® national managed care database that contains medical and pharmacy claims, eligibility data, and laboratory results for 107 million patients in the United States. Outcomes evaluated were A1c levels, treatment persistence (the proportion of patients that stayed on study drugs during the follow-up period without discontinuing or switching), hypoglycemia, healthcare resource utilization, and healthcare costs.

Data from a total of 62,644 patients were included in the analysis. Patients ≥18 years of age with T2DM who had initiated basal insulin therapy between January 1, 2001, and December 31, 2011, met eligibility requirements. Patients had to have been enrolled in a health plan 6 months before (baseline period) and 12 months after (follow-up period) initiation of insulin therapy. Patients must have received ≥1 prescription for an OAD during the baseline period. During the baseline period, 16,481 patients (26.3%) were treated with 1 OAD (the 1OAD group), 25,336 (40.4%) were treated with 2 OADs (the 2OADs group), and 20,827 (33.2%) were treated with 3 or more OADs (the 3+ OADs group). Mean A1c levels were >9.0% in each of the 3 groups.

When compared with patients in the other 2 groups, patients in the 1OAD group were more likely to be younger, female, and sicker as measured by the Charlson comorbidity index. They were also more likely to have macrovascular disease (myocardial infarction, congestive heart failure, peripheral vascular disease, cerebrovascular disease), obesity, and mental illness. The members of the 1OAD group were less likely to have microvascular disease (neuropathy and retinopathy), hypertension, and hyperlipidemia.

In the 2OADs group, the most common OADs were metformin and sulfonylureas (SU) (59.0%) and metformin and TZD (thiazolinediones) (13.2%). In the 3+ OADs group, the most common OADs were metformin and SU and TZD (66.2%) and metformin with SU and a dipeptidal peptidase 4 (DPP-4) inhibitor (10.0%). Significantly more patients in the 2 and 3+ OADs group used insulin glargine or insulin detemir compared with those in the 1OAD group, while significantly more patients in the 1OAD group initiated therapy with NPH or Lente insulin compared with the other groups.

Persistence with insulin treatment was significantly lower for 1OAD patients compared with 2 OADs or 3+ OADs patients (67.1% vs 76.1% and 82.0%, respectively; P<.0001 for both comparisons). At the end of 1-year follow-up, despite lower treatment persistence, patients in the 1OAD group experienced significantly greater reductions in A1c than those in the other groups.

A significantly greater proportion of patients in the 1OAD group was hospitalized or had an emergency department visit during baseline and follow-up compared with the other groups (P<.0001). With the exception of endocrinology visits, healthcare utilization decreased for all groups with initiation of insulin therapy.

This study was supported by Sanofi.