Little Adjuvant Drug Use in Type 1 Diabetes, Study Shows

Marlene Busko

August 10, 2017

Reported rates of off-label prescribing of antihyperglycemic drugs in addition to insulin for patients with type 1 diabetes were low in European and American registries, investigators report in a research letter published online August 2 in Diabetes Care.

The rates of adjuvant drug use were higher in the United States than in Europe. In the T1D Exchange (T1DX) registry in the United States, 5.4% of patients were receiving adjuvant therapy for type 1 diabetes, compared with 1.6% of patients in the Prospective Diabetes Follow-up (DPV) registry in Germany and Austria (P < .001).

The adjuvant drugs included metformin, glucagonlike peptide 1 (GLP-1) receptor agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors, sodium–glucose cotransporter 2 (SGLT2) inhibitors, and other medications approved for type 2 diabetes but not type 1 diabetes.

Many patients with type 1 diabetes have suboptimal glycemic control, and the use of these adjuvants has been proposed to improve glycemic control, reduce insulin dose, promote weight loss, and treat polycystic ovarian syndrome, Sarah K Lyons, MD, from Baylor College of Medicine, in Houston, Texas, and colleagues write.

Unfortunately, the database did not provide information about reasons for use, Dr Lyons told Medscape Medical News.

"These are medications that aren't currently approved for type 1 diabetes that are being clinically a small proportion of individuals," she said. "We are now able to say these are more commonly used in adults vs [youth] and that metformin is the most commonly reported medication."

Prescribing Snapshot

Although use of adjuvant therapy to improve glycemic control for patients with type 1 diabetes has been reported, it has not been clear how common this is in clinical practice.

To investigate this, the researchers identified 19,298 patients at 73 T1DX sites and 30,698 patients at 354 DPV sites who had type 1 diabetes for at least a year and for whom data was obtained from April 2015 to July 2016.

Dr Lyons and colleagues found that the rates of adjuvant use were higher in the United States than in Europe, overall, and for each age group.

The most commonly prescribed adjuvant was metformin, which was prescribed for 3.5% of patients in the T1DX registry and 1.3% of patients in the DPV registry (< .001).

In the T1DX registry, the next most common adjuvants were GLP-1 agonists (0.91% of patients), SGLT2 inhibitors (0.63%), and DPP-4 inhibitors (0.04%).

In contrast, in the DPV registry, the next most common adjuvants were DPP-4 inhibitors (0.13%), SGLT2 inhibitors (0.13%), and GLP-1 agonists (0.07%).

Some patients received pramlintide (only in the T1DX registry), sulfonylureas, and incretin therapy of unknown type, and some patients were given more than one type of adjuvant.

In the US registry, the highest rate of adjuvant use, at 12.1%, was among patients aged 26 to 49 years, whereas in the European registry, the highest rate of use, at 7.0%, was among patients who were 50 or older.

Need Prospective Study

"Further prospective study of the patterns of adjuvant pharmacotherapy use and the long-term impact on metabolic control is needed in patients with [type 1 diabetes]," the researchers conclude.  

Other recent research is examining the use of metformin and a novel agent as an add-on therapy in type 1 diabetes. As previously reported, the REMOVAL trial presented mixed data on the cardiovascular benefits of metformin as adjunctive therapy in type 1 diabetes, at the recent American Diabetes Association (ADA) 2017 Scientific Sessions.

And at the same meeting, researchers presented "encouraging" phase 3 data for the use of the first-in-class sodium-glucose cotransporter types 1 and 2 (SGLT1/2) inhibitor sotagliflozin  (Lexicon and now Sanofi), which is being developed specifically as an add-on therapy for type 1 diabetes.

The authors report no relevant financial relationships.  

Diabetes Care. Published online August 2, 2017. Article

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