Medicine is a powerful way of shaping the invisible world, and in that power lie both medicine's benefit and its limitation. Teaching and learning medicine are unusually complex, and present subtle changes. The 41 essays in Who Has Seen a Blood Sugar? are not directly concerned with teaching methods and techniques. Rather, each takes as its starting point some particularly critical or problematic element of medical education, develops new and different ways of thinking about it, and explores better ways to approach it. Many of these insights come from sources outside medicine, from fields as diverse as mathematics, linguistics, poetry, music, philosophy, and literature. All essays are referenced, pointing readers to additional sources of background material and detail. In fact, the nearly 250 references may be of special interest and use to readers.