Predictors of Insulin Initiation in Patients with Type 2 Diabetes: An Analysis of the Look AHEAD Randomized Trial
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The decision to initiate insulin in patients with type 2 diabetes is a challenging escalation of care that requires an individualized approach. However, the sociodemographic and clinical factors affecting insulin initiation are not well understood.
We sought to identify patient factors that were independent predictors of insulin initiation among participants in the Look AHEAD (Action for Health in Diabetes) clinical trial.
Retrospective analysis of a randomized clinical trial.
Beginning in 2001, Look AHEAD enrolled ambulatory U.S. adults with type 2 diabetes who were overweight or obese and had a primary healthcare provider. Participants were randomized (1:1) to an intensive lifestyle intervention, or diabetes support and education. This study examined 3913 participants across the two trial arms who were not using insulin at baseline.
We used Cox proportional hazards models to estimate the association between participant characteristics and time to insulin initiation. We performed time-varying adjustment for HbA1c measured eight times over the 10-year study period, as well as for multiple clinical and socioeconomic factors.
A total of 1087 participants (27.8%) initiated insulin during a median follow-up of 8.0 years. Age was inversely associated with insulin initiation (adjusted hazard ratio [aHR] 0.88 per 10 years, P = 0.025). The risk of insulin initiation was greater with a higher number of diabetes complications (P < 0.001 for trend); chronic kidney disease and cardiovascular disease were independently associated with insulin initiation. There was a lower risk of insulin initiation in black (aHR 0.77, P = 0.008) and Hispanic participants (aHR 0.66, P < 0.001) relative to white participants. Socioeconomic factors were not associated with insulin initiation.
Patient age, race/ethnicity, and diabetes complications may influence insulin initiation in type 2 diabetes, independent of glycemic control. Future work is needed to understand the drivers of racial differences in antihyperglycemic treatment, and to identify patients who benefit most from insulin.
KEY WORDSdiabetes mellitus, type 2 insulin/therapeutic use risk factors pharmacoepidemiology
S.J.P performed the data analysis and prepared the manuscript. H.Y. contributed to the methods and reviewed/edited the manuscript. J.M.C. contributed to the study design, data collection, methods, and discussion, and reviewed/edited the manuscript. S.P.J. and N.M.M. contributed to the methods and discussion, and reviewed/edited the manuscript. The authors thank Moyses Szklo, MD, DrPH, of the Johns Hopkins Bloomberg School of Public Health for contributions to the design and interpretation of this work. S.J.P. is the guarantor of this work and, as such, had full access to the data and takes responsibility for the accuracy and integrity of this research.
S.J.P. was supported by NIH training grant 5T32HL007180-40 (PI: D. Levine). S.P.J. was supported by NIH/NIDDK grant T32DK007732 (PI: L. Appel). J.M.C. and N.M.M. were supported by NIH/NIDDK grant 2U01DK057149-17 (PI: J. Clark).
Compliance with Ethical Standards
Parts of this research were presented as an oral presentation at the Society of General Internal Medicine Annual Meeting on April 21, 2017.
Conflict of Interest
The authors declare that they do not have a conflict of interest.
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