medwireNews: The proportion of individuals receiving second-line therapy for diabetes has decreased over time despite worsening glycemic control over the same period, US study findings indicate.
“Our findings are consistent with worsening therapeutic inertia over time early in the care of patients with diabetes,” write Sridharan Raghavan (University of Colorado Anschutz Medical Campus, Aurora) and co-authors in Diabetes Care.
The researchers studied data from 199,042 adults (median age 62.6 years, 96% men) with newly diagnosed type 2 diabetes in the US Department of Veterans Affairs healthcare system who began treatment with metformin monotherapy between 2005 and 2013.
Among those who initiated metformin in 2005, 47% were given a second-line therapy during the subsequent 5 years. The proportion was significantly lower, at 36%, among individuals who initiated metformin in 2013.
Furthermore, after adjustment for age at diabetes diagnosis, race, sex, and BMI and creatinine level, the likelihood of starting a second-line treatment among people who initiated metformin in 2006 was a significant 10% lower than those starting metformin in 2005. For the 2013 cohort, the likelihood was a significant 32% lower than that for the 2005 group.
The researchers also observed that second-line treatment initiation was significantly less common in people over 55 years of age than their younger counterparts, but the same temporal trends applied.
In addition to decreasing proportions of people initiating second-line glucose-lowering therapy, Raghavan and team found that glycated hemoglobin (HbA1c) levels at the time of both metformin and second-line treatment initiation increased significantly with time.
At baseline, mean HbA1c ranged from 7.2% to 7.4% (55 to 57 mmol/mol), with the lowest level recorded among metformin initiators in 2008 and the highest for those starting in 2013; baseline HbA1c increased by a gradual but significant 0.014% per year.
At the time of second-line treatment initiation, mean HbA1c was 7.7% (61 mmol/mol) in the 2005 metformin initiators compared with 8.6% (70 mmol/mol) in their 2013 counterparts, with mean HbA1c increasing by a significant 0.086% per year.
There was no significant interaction between age and HbA1c at second-line treatment initiation, but the researchers point out that “[t]he temporal trend in younger individuals [≤55 years] was particularly striking, with the mean HbA1c exceeding 9% at the time of second-line treatment initiation among metformin initiators in 2012 and 2013.”
They say: “In combination with evidence of long-term benefit of early glycemic control, diabetes care guidelines support more intensive glycemic control for younger patients, making the adverse temporal trends in second-line treatment initiation among younger individuals in our study a potentially concerning indicator of suboptimal diabetes care.”
At the end of the 5-year follow-up period mean HbA1c ranged from 6.9% (52 mmol/mol) in the 2005 cohort to 7.1% (54 mmol/mol) in the 2013 cohort.
“The increases in HbA1c at metformin initiation from 2005 to 2013, at second-line treatment initiation, and in time to second-line treatment initiation over successive years portend potentially adverse long-term population health for veterans with diabetes,” Raghavan et al remark.
They conclude: “Measures are needed to promote earlier guideline-directed diabetes treatment modification in individuals without adequate glycemic control on initial metformin monotherapy.”
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