The majority of people with type 2 diabetes and renal impairment are not receiving doses of non-insulin diabetes medications in line with current guidelines.
A cross-sectional study of 3,505 Australians with type 2 diabetes and an average eGFR in the 30-59ml/min/1.73m2 range found 59% were prescribed at least one medication in a dose inconsistent with ADS guidelines.
The study found the drug classes with the highest proportion of inconsistent dosing were SGLT2 inhibitors (83%), biguanides (58%) and DPP4 inhibitors (46%).
And 79% of patients prescribed a combination product such as metformin and sulphonylureas or metformin and DPP4 inhibitors had a dose inconsistent with the guidelines.
The study found higher HbA1c, longer duration of diabetes and the presence of retinopathy were associated with the likelihood of dosing inconsistent with guidelines.
Lead researcher Dr Jo-Anne Manski-Nankervis told the limbic it was possible that the increased complexity around management of longstanding diabetes may lead people to try other options to reach glycaemic targets.
And it was not necessarily true that prescription of doses inconsistent with guidelines were inappropriate for every patient.
However eGFR needed to be checked regularly and dose adjustments considered – including for combination products.
“Convenience is really important and those combination products for patients can also often make those medications more affordable so I would never suggest not prescribing combination medications.”
“I think what we are saying is that if you are prescribing combination medication to patients, before you provide the next repeat script it is work checking that eGFR and making sure that the different individual components are still suitable for the patient.”
Dr Manski-Nankervis, from the University of Melbourne’s Department of General Practice, said there might be more caution with prescribing if adverse outcomes were more serious or better understood.
“Some of the issues that may underpin some of these results are that, for example, the risk of lactic acidosis with metformin has probably been overstated in product information.”
“And with the SGLT2 inhibitors, whilst they might not be very effective in helping people reach glycaemic targets when people have impaired renal function, there has been some evidence that there might be some improved cardiovascular outcomes that may be independent of that. That may be an explanation for why people are giving those a shot.”
More qualitative work was needed to further understand prescribing behaviours along with linkage studies between GP and hospital datasets to look for adverse outcomes.
Dr Manski-Nankervis added that making guidelines more available at the point of care, perhaps with more advanced clinical decision support, would help optimise prescribing.