Final answer:
Urine can smell ammoniacal due to protein breakdown, and fruity in cases of diabetes mellitus from excessive ketones like acetone. High ketone levels indicate the body is using fat for energy instead of glucose, common in untreated diabetes.
Step-by-step explanation:
Urine may develop an ammoniacal smell if allowed to stand due to the breakdown of proteins, and urine may smell fruity due to the presence of ketoacids in a person with diabetes mellitus.
Normal urine is clear and transparent. However, if urine is left to stand, bacteria can break down urea into ammonia, leading to a strong ammonia odor. In the case of diabetes mellitus, when cells are unable to utilize glucose efficiently due to lack of insulin in type I diabetes or insulin resistance in type II diabetes, the body resorts to fat metabolism, producing ketoacids such as acetone, which can give urine a fruity odor.
Ketones are byproducts of fat metabolism, and when ketones are excreted in the urine, a condition known as ketonuria, it may indicate that the body is using fat for energy instead of glucose. This condition is prevalent in those with untreated or poorly managed diabetes mellitus, where the cells cannot take up glucose and thus fats are metabolized, leading to excessive ketone production and a fruity-smelling urine.