In the wake of the recent annual European diabetes (EASD) meeting, another important study (and heavy science blog post!) coming your way today. 
In the care of people with type 2 diabetes, we have fully 9 classes of glucose lowering medications to choose from in Canada.  While some of these medications can cause weight gain, others are weight neutral, and some can cause weight loss, in addition to improving blood sugar control.  Two classes of medications can cause weight loss, namely the GLP1 receptor agonists, and the SGLT2 inhibitors.  As 90% of people with type 2 diabetes also have overweight or obesity, it is of interest to know whether these two classes of medications can be used together, for even better blood sugar control and greater weight loss.
Two of these medications, the GLP1 receptor agonist exenatide qweekly (Bydureon) and the SGLT2 inhibitor dapagliflozin (Forxiga) have now been studied in combination.  Recently published in The Lancet Diabetes & Endocrinology, the study randomized 695 patients with a baseline hemoglobin A1C of 8-12% to receive either exenatide qweekly, dapagliflozin, or the two medications in combination. 
After 28 weeks, hemoglobin A1C decreased by 1.6% in the exenatide group, by 1.4% in the dapagliflozin group, and by 2.0% in the combination group.   While the medications together were better
than either drug alone, the benefit was not additive.  This does not surprise us, as we know that the higher starting A1C, the greater reduction we will see – so to be on two medications together would not expect to give an additive result compared to either medication alone.
The weight loss seen was additive, with a loss of -1.54kg in the exenatide group, -2.19kg in the dapagliflozin group, and -3.41kg in the combination group. Blood pressure reduction also exhibited an additive response, with a systolic BP reduction of -1.3mmHg on exenatide, -1.8mmHg reduction on dapagliflozin, and a full -4.2mmHg reduction on the combination.  These additive benefits make sense, given that each of these medications has a different mechanism of action on weight and blood pressure.
From a safety point of view, side effects that were seen were as expected from what we already know about each of these classes of medications, with no suggestion for any negative side effects of using the two medications in combination.
Finally, we have much awaited data that shows us that these two medications can be used safely in combination, with the result of better diabetes control, and an additive effect on both weight loss and blood pressure.

Disclaimer: I am involved in research trials of GLP-1 receptor agonists and SGLT2 inhibitors.  I receive honoraria as a continuing medical education speaker and consultant from the makers of exenatide and dapagliflozin (Astra Zeneca). 

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