Effect of patients' risks and preferences on health gains with plasma glucose level lowering in type 2 diabetes mellitus

Abstract

Importance: Type 2 diabetes mellitus is common, and treatment to correct blood glucose levels is standard. However, treatment burden starts years before treatment benefits accrue. Because guidelines often ignore treatment burden, many patients with diabetes may be overtreated.

Objective: To examine how treatment burden affects the benefits of intensive vs moderate glycemic control in patients with type 2 diabetes.

Design, setting, and participants: We estimated the effects of hemoglobin A1c (HbA1c) reduction on diabetes outcomes and overall quality-adjusted life years (QALYs) using a Markov simulation model. Model probabilities were based on estimates from randomized trials and observational studies. Simulated patients were based on adult patients with type 2 diabetes drawn from the National Health and Nutrition Examination Study.

Interventions: Glucose lowering with oral agents or insulin in type 2 diabetes.

Main outcomes and measures: Main outcomes were QALYs and reduction in risk of microvascular and cardiovascular diabetes complications.

Results: Assuming a low treatment burden (0.001, or 0.4 lost days per year), treatment that lowered HbA1c level by 1 percentage point provided benefits ranging from 0.77 to 0.91 QALYs for simulated patients who received a diagnosis at age 45 years to 0.08 to 0.10 QALYs for those who received a diagnosis at age 75 years. An increase in treatment burden (0.01, or 3.7 days lost per year) resulted in HbA1c level lowering being associated with more harm than benefit in those aged 75 years. Across all ages, patients who viewed treatment as more burdensome (0.025-0.05 disutility) experienced a net loss in QALYs from treatments to lower HbA1c level.

Conclusions and relevance: Improving glycemic control can provide substantial benefits, especially for younger patients; however, for most patients older than 50 years with an HbA1c level less than 9% receiving metformin therapy, additional glycemic treatment usually offers at most modest benefits. Furthermore, the magnitude of benefit is sensitive to patients' views of the treatment burden, and even small treatment adverse effects result in net harm in older patients. The current approach of broadly advocating intensive glycemic control should be reconsidered; instead, treating patients with HbA1c levels less than 9% should be individualized on the basis of estimates of benefit weighed against the patient's views of the burdens of treatment.

Figure 1

QALYs gained or lost by age and treatment burden This figure relates the QALYs gained or lost by a treatment that leads to a 1% reduction in A1c (from 8.5% to 7.5%) across 4 age groups and views of the burden of treatment.

Figure 2

Sensitivity analysis This figure demonstrates the variability in gains in QALYs from a 1% reduction in A1c for various age, utility, and starting A1c values.