If your blood glucose level is higher than 250 mg/dl, you do not have ketones in your blood or urine, and you want to exercise, I recommend starting your workout then stopping after 15 minutes to see if your blood glucose level is rising or dropping.
Outfielder Ty Cobb, whose career ended in 1928, has the highest batting average in Major League Baseball (MLB) history. He batted .366 over 24 seasons, mostly with the Detroit Tigers. In addition, he won a record 11 batting titles for leading the American League in BA over the course of an entire season.
Highest batting average for a career is .366 by Ty Cobb (1905-1928). Highest batting average for a season in the dead ball era is .4397 by Hugh Duffy in 1894 (age 27). Highest average in a season in the modern era is .406 by Ted Williams in 1941 (age 22). Highest batting average in the National League for 2012 was .336 by Buster Posey (age 25). The highest batting average in the American League in 2012 was .330 by Miguel Cabrera (age 29). Edit: Subtopics added on this question.