Final answer:
The topic of Schoenthaler's study in 1985 related to blood sugar levels was the effect of diet on blood sugar levels.
Step-by-step explanation:
The topic of Schoenthaler's study in 1985 related to blood sugar levels was the effect of diet on blood sugar levels. In his study, Schoenthaler examined the relationship between diet and blood sugar levels, specifically looking at how different dietary choices can impact blood sugar regulation. This study provided valuable insights into the role of diet in managing blood sugar levels and the importance of making healthy food choices to maintain a stable blood sugar level.