Maddening!

just when I begin to think that I am somewhat getting this under control. My fbs for the past month or so has been in the very low 100's (<110) However now about every other day when I check it it is like 130+ for NO APPARENT REASON. When it is high like that it goes back down during the day till late at night it is back to 101 or something like that. I eat a very lc diet, (about 10-30). my exercise varies from walks to working in the yard. It is just downright frustrating to get up, test myself and see those high numbers.