Sweet-smelling urine most commonly signals that glucose or ketones are present in your urine, often pointing to uncontrolled blood sugar. But it can also come from something as harmless as a supplement you’re taking. The cause matters, because some explanations are benign and others need prompt attention.
Glucose Spilling Into Your Urine
Your kidneys normally filter glucose out of your blood and reabsorb it back into your body. But when blood sugar rises above roughly 180 mg/dL, your kidneys can’t keep up. Glucose starts spilling into your urine, a condition called glycosuria, and it can give urine a noticeably sweet smell. In people with insulin-dependent diabetes, that threshold can be considerably lower, averaging around 130 mg/dL, with some individuals spilling glucose at levels as low as 54 mg/dL.
This is the most common medical reason for sweet-smelling urine, and it often shows up before a person realizes their diabetes is poorly controlled or even before they’ve been diagnosed. If the sweet smell persists over multiple bathroom trips, especially alongside increased thirst and frequent urination, elevated blood sugar is the first thing to rule out.
Ketones and a Fruity Scent
When your body can’t use glucose for energy (because of insufficient insulin or prolonged fasting), it starts burning fat rapidly instead. That process generates acidic chemicals called ketones, which build up in your blood and eventually spill into your urine. High ketone levels produce a distinct fruity or sweet odor that you may notice in both your breath and your urine.
In people with type 1 diabetes, this can escalate into diabetic ketoacidosis, a dangerous condition where acid accumulates in the blood faster than the body can clear it. Ketoacidosis is a medical emergency. If sweet or fruity-smelling urine is paired with nausea, vomiting, confusion, or abdominal pain, that combination needs immediate care. People following very low-carb or ketogenic diets can also produce enough ketones to change their urine’s smell, though this is typically mild and not dangerous on its own.
Medications That Cause It
A class of diabetes drugs called SGLT2 inhibitors works by deliberately forcing glucose out through your urine. These medications, which include canagliflozin, dapagliflozin, and empagliflozin, block the kidney’s ability to reabsorb filtered glucose by 30% to 60%. The result is significantly more sugar in your urine, which can make it smell sweet. If you recently started one of these medications and noticed the change, that’s the likely explanation. It’s an expected side effect, not a sign that something is going wrong.
Fenugreek and Dietary Causes
Fenugreek, a common herbal supplement used to support lactation, manage blood sugar, or boost libido, contains a compound called sotolone. This is the same chemical responsible for the aroma of maple syrup, caramel, and certain aged rums. When you consume fenugreek in supplement form, sotolone passes through your body and can give your urine (and sometimes your sweat) a distinctly sweet, maple syrup-like smell.
This effect is well-documented and harmless. In clinical trials of fenugreek supplements, a maple syrup odor in urine was the single most commonly reported side effect. It has even shown up in breastfed infants whose mothers were taking fenugreek. The smell typically fades within a day or two of stopping the supplement. If you’ve recently added fenugreek to your routine, whether as capsules, tea, or a spice used generously in cooking, that’s very likely your answer.
Pregnancy and Gestational Diabetes
During pregnancy, hormonal shifts can affect how your body processes insulin, sometimes leading to gestational diabetes. When blood sugar rises high enough for glucose to enter the urine, you may notice a sweet smell. Gestational diabetes rarely causes obvious symptoms on its own, so a change in urine odor can be one of the first things a person notices. Increased thirst and more frequent urination are the other common signs. Standard prenatal care includes screening for gestational diabetes, typically in the second trimester, so it’s usually caught whether or not you notice symptoms.
Maple Syrup Urine Disease
This is a rare genetic condition, but it’s worth knowing about because the name describes the symptom exactly. People with maple syrup urine disease lack the enzyme needed to break down three specific amino acids found in protein. When those amino acids build up, a byproduct called sotolone (the same compound found in fenugreek) accumulates in body fluids and produces a sweet, syrupy smell in urine, sweat, and earwax.
This condition is almost always identified in newborns through routine screening. In infants, early signs include the characteristic smell, poor feeding, lethargy, and irritability. Without treatment, it can progress to seizures, coma, and death. Even children and adults already managing the condition can experience flare-ups triggered by infections, injuries, or stress. While it’s unlikely to be the explanation for an adult who’s never been diagnosed, it’s the reason sweet-smelling urine in a newborn should always be treated as urgent.
Bacterial Infections With a Sweet Odor
Certain urinary tract infections can change how your urine smells, and one bacterium in particular produces a notably sweet scent. Pseudomonas aeruginosa, which causes 7% to 15% of UTIs, generates compounds that create a grape-like, sweet odor. This bacterium was first identified in the 1850s partly because of its distinctive smell on surgical dressings. A sweet-smelling UTI would typically come with other symptoms like burning during urination, cloudy urine, pelvic pressure, or fever.
What the Smell Tells You
A one-time sweet smell after eating certain foods or taking supplements is rarely concerning. What matters is persistence and context. Sweet-smelling urine that shows up repeatedly over several days, particularly alongside increased thirst, frequent urination, unexplained weight loss, fatigue, or nausea, points toward a blood sugar problem that needs evaluation. A simple urine dipstick test can detect glucose and ketones in minutes, and a basic blood sugar check can confirm or rule out diabetes quickly.
If you’re pregnant and haven’t had your glucose screening yet, mention the symptom at your next prenatal visit. If the smell is accompanied by confusion, vomiting, or rapid breathing, those are signs of ketoacidosis and warrant emergency care rather than a scheduled appointment.