Well it could be a multitude of things...
As others have suggested tighten up your control, reduce the deviation from your target blood sugar and try to smooth things out.
Also make sure you are sleeping, eating well, drinking lots of water etc and are generally living a healthy lifestyle.
Also I would advise relax and try to stop thinking about it, it could be an anxiety issue as well :)
Perhaps get a check up/MOT from your Dr, just in case something else is up .
Failing that Sildenafil Citrate in its various guises should do the job if all else fails :)