Yeah, that sounds good for diabetes, not for ketosis. You're burning carbs, and when your riding hard you need more. Try adding a little bit of carbs on the bike (eat during the ride) and see if you can hit the hills harder. Since your muscles are pulling the sugar out of your blood, it should not effect your diabetes control. Test your blood sugar pre and post, see what happens.
I imagine you're tracking your speed with GPS, if you use Strava or the like you may see faster times on hill segments with some carbs on board