Smelly urine is not a symptom of diabetes; however, diabetics may notice a sweet smell in their urine, due to excess sugar, notes WebMD. In fact, early medical doctors tasted patients' urine for sweetness as a method of diagnosing diabetes.
Normal urine does not have a strong smell, advises WebMD. Foul-smelling urine may be symptomatic of urinary stones or a urinary infection, both of which create an odor similar to ammonia. In addition, dehydration concentrates the urine more than normal, giving urine a stronger ammonia scent due to increased waste, according to Mayo Clinic. Some rare genetic disorders also cause urine to take on a strange or abnormal odor.
Some people experience a change of urine odor when eating asparagus, notes WebMD. The foul-smelling urine caused by eating asparagus comes from the breakdown of methyl mercaptan, the same sulfur compound found in skunk secretions and garlic. Not everyone who eats asparagus experiences an altered urine smell from it; only people who inherit the gene for the enzyme that the body uses to break down mercaptan are affected.
Other causes of unusual-smelling urine include bladder infections, bladder inflammation and gastrointestinal bladder fistulas, notes Mayo Clinic. Metabolic disorders and maple syrup urine disease are additional causes.