Ladies, anyone have patch of hair loss?

My sister has a small patch of hair that is thinning and becoming sparce, above her temple. With hairline there slightly receeding. Shes unsure why she's having the hair loss..possibly her high blood sugars? She's diabetic. Possibly stress she has from ongoing emotional issues plus an undiagnosed leg condition? Anyone experienced this type hair loss or know causes? And what did you use to help it regrow?