Sugar and heart rate

I haven't had much soda, or we'll anything with sugar to drink for that matter, in almost 3 months, since I started getting heart palpitations. I had probably half of a large sprite from wendys, ( bad Idea, I know ) and my heart rate went up to 109, nor a HORRIBLY high rate, but enough to make go "what is going on?" It's since gone down go 90-99, about an hour later, despite not being thirsty I'm trying to drink as much water as possible. Has anyone else had this happen? I've had to cut out almost all sugar due to pre-diabetes. It's also very warm here, and most of the time when it's warm, my heart rate does go up, so I'm sure it's just a combination of both. But I've made a promise to myself not to Google symptoms, so I figured here was my best bet.