Glucose or sugar isn’t normally present in urine, since normally all the glucose is re-absorbed by the kidneys as part of normal renal function. Various factors determine the composition of urine, besides how well the kidneys function. For example, what and how much one drinks and eats, the amount of exercise taken, and certain medications can all affect urinary composition. Keeping well-hydrated and well-nourished are as important for urinary health as for general wellness.
While glucose can be present in otherwise normal urine in very small amounts, or not all, an abnormally high amount (glycosuria) is generally indicative of high blood glucose (blood sugar) levels and some or other underlying pathology.
There are certain common conditions and/ or health disorders that can lead to glycosuria, as well as a range of more uncommon conditions. The most common causes include hyperglycaemia (high blood sugar levels), pre-diabetes (abnormal glucose levels without all the symptoms of diabetes), and diabetes (a condition in which the body’s ability to use sugar for energy is impaired). A serious or life-threatening cause of too much glucose in urine is uncontrolled diabetes. The excess blood sugar/glucose ‘spills over’ into the urine, so to speak, and requires immediate medical attention. Urinary tract infections (UTIs) – such as cystitis – may occur more frequently if glucose is present in the urine, since sugar provides fertile fodder and an optimal breeding ground for bacteria, which is why people with type 2 diabetes are at higher risk for UTIs than non-diabetics. So, keeping blood glucose under control helps to keep urinary glucose under control, which in turn minimises urinary infections.
Some people have a low renal threshold, i.e. their kidneys are unable to deal with a normal glucose load and instead of recycling the glucose back into the systemic circulation via the bloodstream, some of it gets excreted into the urine. Although a trace of glucose may be present in a healthy pregnant woman’s urine, high glucose levels can indicate gestational diabetes, which is a serious condition that requires careful professional monitoring.
Kidney disease like nephrotic syndrome, as well as kidney transplant, renal glycosuria, adrenal gland problems, brain injury, liver damage, and certain types of poisoning are relatively rare conditions that can also result in elevated urinary glucose levels.
A simple dipstick test is usually used to check for glucose (and other substances) in the urine – either via your doctor, clinic or personally at home. Some pharmacies sell dipstick urine test kits without the need for a prescription. While such a test is a useful starting point for exploring urine composition, a full urinalysis can be conducted by a pathology laboratory. The latter can more specifically identify urinary abnormalities than a simple dipstick test. If you do have glucose in your urine it is advisable to visit a diagnostic health care practitioner to further explore the cause/make a diagnosis, and advise you on what is needed to bring your glucose levels back in balance.
I hope this helps to answer your question.