Background:
Prior studies have demonstrated that insulin glargine produces less hypoglycemia, as compared with NPH. Whether these results translate into better long-term cardiovascular outcomes in patients with Type 2 diabetes is unknown.
Methods:
Using a national managed care administrative database, we evaluated patients with Type 2 diabetes who were on oral antiglycemic agents within 6 months prior to initiating either insulin glargine (n=15,039) or NPH (n=5,666) and had at least 12 months of subsequent continuous plan enrollment during 03/2001–03/2005. Cox proportional hazard models were used to compare the rate of subsequent myocardial infarction (MI) events (defined by ICD-9 codes) following initiation of glargine vs NPH, after adjusting for demographic characteristics, comorbidities, other medications, insulin adherence and baseline Hemoglobin A1C (A1C).
Results: Mean age was 56 years, 49% were women; mean duration of follow up was 24 months. Among patients who had available A1C (n=2514), those in glargine group had higher A1C at baseline vs. NPH (9.3 vs 8.9 respectively, p<0.0001). During the 1
st
year following insulin initiation, 8.7% patients in NPH vs. 7.5% in glargine group had at least one medical claim for hypoglycemia (OR=1.17, 95% CI: 1.05–1.31). In unadjusted analysis, the rate of MI events was 4.4% in glargine group vs. 7.7% in the NPH group (p<0.0001). After multivariable adjustment, risk of MI events remained lower in glargine group (HR: 0.78, 95% CI: 0.64–0.95). Although hypoglycemic events were associated with higher MI risk (HR 1.3, 95% CI 1.18–1.44 for each quarter with a medical claim for hypoglycemia during 1
st
year of follow up), the association between glargine use and lower risk of MI events remained significant even after adjusting for hypoglycemia (HR: 0.79, 95% CI 0.65–0.96).
Conclusion:
Initiation of insulin glargine in patients with Type 2 diabetes is associated with lower risk of subsequent MI events, as compared with NPH. Lower rate of hypoglycemia associated with glargine use does not completely account for this difference in outcomes. Further studies are needed to validate these results and provide insights into potential physiologic mechanisms.
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