Measuring the amount of sugar in your bloodstream is a normal part of everyday life with type 1 or type 2 diabetes. Measuring the sugar in your urine, however, is something we should be doing every now and then at the doctor’s office, too.
In this article, we’ll discuss what “glycosuria” is, what causes it, signs and symptoms, and how it’s treated.
What is glycosuria?
Glycosuria is a term to describe the presence of glucose (sugar) in your urine — which can be tested easily with a urine sample at your next appointment with your primary healthcare team.
Normally, the renal tubes in your kidneys act as a filter to remove excess glucose from your system before it passes through to your urine.
“With normal renal (ie. kidney) function, as blood flows through the kidneys, glucose and other substances are filtered from the fluid portion of the blood,” explains National Organization for Rare Diseases (NORD).
“The filtrate of the blood then moves through a network of canals known as renal tubules, where most of the filtered substances, including glucose, sodium, and water, are reabsorbed and returned to the bloodstream, while certain unwanted substances are eliminated in the urine.”
It is normal for a healthy adult to excrete some glucose through your urine — about 65 milligrams of glucose per day — because while your kidneys absorb most of the glucose that passes through, it cannot absorb all of it.
65 milligrams may sound like a lot, but n fact, it’s such a small amount, that medical technology can’t even measure it.
When glucose levels in your urine begin rising above this amount, however, it indicates a problem — either with your kidneys or with your blood sugar.
Let’s take a closer look at what causes glycosuria.
What causes glycosuria?
For people with any type of diabetes — and especially women with diabetes who are pregnant — having the glucose levels of your urine tested at least once a year is important.
There are four likely causes of glycosuria in people with diabetes:
High blood sugar levels
When your blood sugar levels are high (either short-term or long-term), the renal tubes in your kidneys simply cannot absorb all of that glucose present, so the excess glucose inevitably passes through your urine.
Short-term, this is the body taking care of itself, but it can lead to other issues, like yeast infections. That glucose encourages the growth of yeast in the vagina (and less common, in the penis).
While a certain amount of yeast is normal, consistently high blood sugars will throw this natural yeast balance out of whack and become an ongoing problem until blood sugar levels come down to a healthier level.
In a person whose kidneys are functioning fully and properly, high blood sugar levels are the only reason you would see measurable amounts of glucose in your urine.
Diabetic renal glycosuria
The other cause of glycosuria is the result of impaired renal (kidney) function. In people with normal blood sugar levels, renal glycosuria is when the renal tubes in your kidneys are not properly absorbing glucose.
This would be referred to as “nondiabetic renal glycosuria.”
In people with diabetes, however, it is most likely related to diabetic kidney disease or “nephropathy.”
The long-term consequences of high blood sugar levels can significantly overwork and damage your kidneys — by damaging the blood vessels and nerve endings in the kidneys and bladder, as well as your urinary tract.
High blood sugar levels also severely affect your kidney’s longterm ability to properly filter your blood.
Eventually, the extra stress this puts on your kidneys can cause leakage through those formerly tiny filter holes. Your kidneys then struggle to filter properly because other things — like protein albumin — are able to get through those holes.
“High sugar levels,” explains the National Kidney Foundation, “can also cause these vessels to become narrow and clogged. Without enough blood, the kidneys become damaged and albumin (a type of protein) passes through these filters and ends up in the urine where it should not be.”
Medications
There are several diabetes medications in the class of “SGLT2 inhibitors” that purposefully cause the kidneys to excrete more glucose through your urine.
Farxiga (dapagliflozin) – Common side-effects: yeast infections, urinary tract infections, increased need to urinate, back pain, nausea, increased cholesterol levels
Invokana (canagliflozin) – Common side-effects: yeast infections, urinary tract infections, increased need to urinate, back pain, nausea, increased cholesterol levels
Jardiance (empagliflozin) – Common side-effects: yeast infections, urinary tract infections, increased need to urinate, back pain, nausea, increased cholesterol levels
Also referred to as “gliflozins,” these drugs work by preventing your kidneys from absorbing the excess glucose in your system so it can be passed through your urine, preventing it from ever entering your bloodstream.
Consequently, this inevitably lowers your blood sugar levels.
Yeast infections are common with these drugs, too, especially if blood sugar levels are extremely high (consistently over 250 mg/dL), because it means there is a significant amount of sugar passing through your urine.
Drinking a lot of water while taking these drugs is important in order to help transport that extra glucose.
Gestational diabetes
In those who don’t have type 1 or type 2 diabetes, glycosuria can be a sign of gestational diabetes.
Gestational diabetes is essentially high blood sugar levels that develop in a woman during pregnancy and return to normal within a few weeks or months after the baby is born.
Gestational diabetes is largely related to diet and weight gain during pregnancy and should be carefully managed with the support of your obstetrics (OB) and maternal-fetal medicine (MFM) team.
Signs and symptoms of glycosuria
In a person with normal blood sugar levels, there could easily be no signs or symptoms of glycosuria. However, glycosuria in people with diabetes will usually include symptoms also related to high blood sugar levels:
- Extreme thirst
- Extreme hunger
- Dehydration
- Incontinence (accidental urination)
- Needing to urinate more frequently
- Needing to urinate in the middle of the night
- Frequent yeast infections
Treatment for glycosuria
The first step in treating glycosuria in people with diabetes is addressing high blood sugar levels.
Working with your healthcare team to reduce your blood sugar levels is critical for all four of the causes listed above.
If your glycosuria is related to diabetic kidney disease, you’ll need to work closely with your nephrology team.
If glycosuria in people with diabetes isn’t the result of a medication, it’s a sign that your blood sugar levels are very high or your kidneys are struggling — and intervention is absolutely necessary.
Ask your doctor to include a urinalysis of the glucose in your urine at your next check-up!
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