Few patients who are initiated on second-line treatment for type 2 diabetes mellitus show evidence of recommended use of first-line treatment with metformin, according to research published online Sept. 13 in Diabetes Care.
A retrospective cross-sectional study examined Aetna member claims data from 52,544 individuals with type 2 diabetes. It showed that of the 22,956 individuals given second-line treatment, only 8.2% had claims evidence of recommended use of metformin in the previous 60 days.
Furthermore, 28% had no claims evidence at all of having taken metformin, and only a small number of these patients had evidence of contraindications to metformin, such as heart failure (2.9%), chronic obstructive pulmonary disease (3.1%), liver diseases (4.3%), or renal diseases (4.1%).
“Although gastrointestinal adverse effects related to metformin therapy might lead to guideline nonadherence and early second-line medication initiation, we did not find evidence for gastrointestinal upset in the claims data,” wrote Yi-Ju Tseng, PhD, of the Computational Health Informatics Program at Boston Children’s Hospital, and her coauthors.
Even at the top range of sensitivity, researchers argued that less than half of the patients on second-line treatment could have had prior recommended use of metformin as the first-line treatment, while at the lower end of sensitivity, that figure was less than 10% (Diabetes Care. 2017 Sep 13. doi: 10.2337/dc17-0213).
Around one-third of patients received some metformin before beginning a second-line treatment, but the duration of metformin treatment was less than the 2 months recommended by current guidelines. Of these patients, just over half were prescribed both metformin and the second-line medication on the same day.
“What may be taken as evidence of treatment failure by clinicians may instead represent failure of adherence to established treatment guidelines, which in turn may lead to the use of insulin or additional second-line medications,” the authors wrote. “Point-of-care decision support and population health–level approaches should focus on improving adherence to first-line therapy.”
The study also found that patients who were given a second-line treatment without evidence of recommended first-line use of metformin were significantly more likely to be given insulin or an additional second-line antihyperglycemic medication. They were also more likely to be male.
However, the authors acknowledged that retrospective claims-based analyses were limited by the exclusion of uninsured patients, and a lack of detailed clinical or behavioral information, or information on out-of-pocket medications.
The study was supported by the National Institute of General Medical Sciences, and one author was supported by grants from the Ministry of Science and Technology, Taiwan and Chang Gung Memorial Hospital, Linkou, Taiwan. No conflicts of interest were declared.