What is Glycosuria?
Glycosuria (or glucosuria) is the presence of glucose in the urine. Glucose is not usually found in the urine; however, certain conditions like diabetes, kidney damage, and renal diseases can increase the risk for glucosuria and result in glucose in urine.
To understand what it means to have glucose in the urine, let's take a step back and understand what glucose is, how it is metabolized and used by the body, and what factors lead to its occurrence in the urine.
Glucose and Metabolism of Glucose
If you imagine something sweet when thinking about glucose, you are right; the term glucose has Greek origins and literally means "sweet." It is a type of sugar derived from carbohydrates, proteins, and lipids. Our bodies process foods to make simple sugars such as glucose, which are further processed by the body to produce energy. It is important to note that glucose does not keep floating in the bloodstream; our bodies efficiently store them in cells for sustained energy release. Our liver is responsible for maintaining a healthy range of glucose levels in the bloodstream. The liver produces insulin (a hormone) which transports glucose to the cells. Insufficient insulin or resistance of cells to respond to insulin can increase blood glucose levels.
How do excess blood glucose levels lead to glucosuria?
Urine is produced by the kidneys. Our kidneys filter the blood, identify waste material from it, and excrete it as urine. The kidneys remove anything in excess to prevent the accumulation or build-up of toxins in the body. In a healthy system, glucose is entirely absorbed by the body (because it is considered a vital energy source). However, if the blood glucose levels are exceedingly high or the kidneys are damaged, glucose may be excreted into the urine, leading to glucosuria.
Glucosuria due to diabetes
In people with diabetes, glucosuria could develop when blood glucose levels run too high, forcing the kidney to pass some of it into the urine. Therefore, a high urine glucose concentration (glycosuria) means your blood glucose level is too high. Abnormally high glucose concentrations in blood and urine are clinically referred to as hyperglycemia and indicate diabetes.
Glucosuria during pregnancy
Gestational diabetes (diabetes during pregnancy) can also result in the secretion of glucose in urine. This could occur due to hormonal and chemical imbalances during the pregnancy and can result in health complications for both mother and the fetus. Prompt management of gestational diabetes is vital to avoid any serious complications.
Glucosuria due to renal or kidney impairment
Genetic and hereditary conditions, such as renal glucosuria, impact the performance of the kidney's filtration process, which could lead to passing glucose in urine. Similarly, any kidney damage or inefficiency in the kidneys' filtration process can lead to passing chemicals in the urine that should not normally appear. All of these factors can lead to glucosuria.
What is the difference between blood and urine glucose levels?
The blood glucose level is a measure of free glucose in your bloodstream, whereas the urine glucose level is a measure of glucose excreted by the kidneys in the urine. Both tests are different and provide complementary information. Glucose in urine is generally not present. However, when the blood glucose levels run very high, glucose is excreted into the urine, resulting in glucosuria. Glucosuria in the absence of diabetes (i.e., high blood glucose levels) is generally attributed to kidney disorders.
Both blood and urine glucose tests are considered essential in the diagnosis of diseases and in assessing the health of organs. It is essential to know that a urine glucose test does not substitute for a blood glucose test. Blood glucose can be easily measured through Point-of-Care Testing, that is, a POCT glucose or POC glucose test using a glucometer. A urine dipstick test, however, is a non-invasive way to measure your urine glucose levels.
In the sections below, we will discuss health conditions that can cause glucose in urine and ways to diagnose and manage glucosuria.
Causes of glucose in urine due to different health conditions:
Glycosuria and Diabetes
Diabetes is of different types. Similar to commonly known Type 1 and Type 2 Diabetes, gestational diabetes (that occurs during pregnancy) and neonatal diabetes (reported under the age of six months) also result in high blood glucose levels. These physically manifest either in the form of hyperglycemia (a technical term for high blood glucose) and/or glycosuria (a technical term for glucose in the urine).
Type 1 Diabetes:
In Type 1 Diabetes, the immune system attacks certain cells in the insulin-producing gland, the pancreas, resulting in insufficient levels of insulin production. Since insulin is essential to carry glucose from the bloodstream to the cells, low levels of insulin lead to the accumulation of glucose in the blood. Unfortunately, excess glucose in the blood cannot be used as an energy source for your body's cells and muscles. Type 1 Diabetes usually develops in childhood or adolescence. If kidneys find excess glucose in the bloodstream, they may excrete it in the urine to prevent organ damage [3].
Type 2 Diabetes:
In Type 2 Diabetes, your body's ability to regulate glucose is affected as it stops responding to insulin. An inadequate supply of insulin from the pancreas could be another possible reason. This results in too much glucose in the bloodstream, risking many body organs, including kidneys, heart, blood vessels, nerves, and eyes. Type 2 Diabetes is often attributed to a sedentary lifestyle and unhealthy food choices. Lack of physical activity, obesity, and consuming sugary foods in excess are the leading causes of type 2 diabetes [8].
Prediabetes:
Prediabetes means having higher-than-normal blood sugar but not high enough to be clinically attributed to diabetes. People often get a pre-diabetes diagnosis before the onset of Type 2 Diabetes. There are no apparent symptoms of pre-diabetes, but its causes and risks are the same as that of Type 2 diabetes (i.e., lack of physical activity, unhealthy diet/lifestyle choices). Adopting a healthy lifestyle and regular medication at this stage can help reverse the condition and lead to full recovery. If not appropriately treated, the condition can gradually deteriorate into Type 2 Diabetes.
Glycosuria in gestational diabetes:
Gestational diabetes relates to glucose in urine during pregnancy. It usually occurs around the sixth month of pregnancy when the blood and urine glucose levels become abnormally high. The cause(s) of gestational diabetes vary from individual to individual, and sometimes there may not be an apparent cause. However, it is generally attributed to hormonal and chemical imbalances due to peculiar pregnancy-related conditions.
Gestational diabetes usually disappears after delivery. However, it is essential not to take it for granted, as gestational diabetes can have short-term and long-term health implications for the expectant mother as well as the baby. For instance, one such complication could be with the size of the baby, which could grow too big for normal delivery and requires a C-section. Scientific studies suggest that women with a history of gestational diabetes are more likely to develop heart disease and Type 2 diabetes later in life.
Renal glycosuria:
Renal glycosuria is an inherited condition related to the kidneys It is not essentially related to your lifestyle and dietary behavior, as is the case with other types. Renal glycosuria happens when your kidneys stop short of filtering the blood sugar, some of which is then passed into the urine.
Diabetes and age:
Anyone — young or old — can have one or the other type of diabetes. But in some cases, age is a factor. Type 2 Diabetes, for example, is also called adult-onset diabetes because of its link with age. Clinical observations suggest that the odds of developing Type 2 Diabetes increase with age. A sizeable percentage of Americans (approximately 14%) are diagnosed with diabetes between 45 to 64 years of age. This number almost doubles after the age of 65. On the other hand, the current global spike in child and teenage obesity (over 157 million worldwide) continues to increase the incidence of diabetes in children and teenagers, much of which can be attributed to poor dietary choices.
Signs and symptoms of glycosuria
Glucose in urine has symptoms common to diabetes. These include:
- Increased thirst and hunger
- Frequent urination
- Weight loss
- Blurred vision
- Slower healing of cuts/wounds
- Fatigue and exhaustion
- Numbness of hands or feet
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How is glucose in the urine tested?
The glucose level in urine is checked through a glucose-in-urine test. Urine glucose test, sugar in urine test, glycosuria, or glucosuria test are different names of the same procedure. You can perform this test at home using urine glucose test strips (urine dipsticks) which come with color-sensitive reagent pads. When dipped in the urine sample, the color of the glucose reagent pad changes to reflect the glucose levels in the test sample5. The color of the pad is then compared with the reference color key that indicates the urine glucose level and provides an interpretation of the results.
The rapid glycosuria dipstick test is a quick and convenient way to determine and monitor glucose levels in the urine. With the help of a glucose urine test strip or a multi-parameter Urinox-10 strip, you can quickly check urine glucose levels and get results in as little as 30 seconds.
How to read the glucose-in-urine dipstick test?
The results of the dipstick test for glycosuria should be read 30 seconds after immersing it in the urine specimen. After wetting the strip in the urine sample, quickly remove it and note the color that appears after 30 seconds. Finally, compare the color of the reagent pad with the color key provided by the manufacturer to interpret the results.
What is the normal range of urine glucose?
The appearance of glucose in the urine means your blood glucose levels are above normal. Normal urine glucose value is 0 to 0.8 mmol/l (0 to 15 mg/dL). Higher urine glucose levels could indicate conditions such as diabetes, pregnancy (gestational diabetes), or renal glycosuria.
How are the test results interpreted?
- A shade of blue or aqua-green on the reagent pad indicates a negative/normal test, with no traces of glucose in the urine;
- A light/dark green or light/dark brown color on the pad indicates a positive test;
- A light green color on the pad indicates trace glucose in urine (5 mmol/L); a further increase (15+ mmoI/L) is shown by dark green color;
- Higher concentrations of glucose, from 30+, 60+, to 110+ mmoI/L, are reflected by changes in the reagent pad color from light brown to brown to dark brown, respectively.
What is the best way forward?
The occurrence of glucose in the urine is not normal. But it does not essentially mean that everyone with the condition is seriously ill. It usually indicates high blood sugar or some problem related to the kidneys. You should not neglect the results either as they can be dangerous for your organ health. A positive test underlines the need to consult your doctor for a proper diagnosis and a course of action to treat and manage your condition.
According to the World Health Organization, high blood glucose (which eventually leads to glycosuria) causes damage to many of the body's systems and organsThese include kidney failure, heart attacks, blindness, stroke, and amputation of the lower limbs. Some studies have linked long-term diabetes with brain function, cognitive difficulties, and vascular dementia.
The best course of action in glycosuria is to go by the cause. For example, if the elevated glucose in urine levels is due to diabetes, the way forward is a healthy diet, regular physical activity, medication, and regular monitoring of glucose levels. Alternatively, if glucosuria is due to compromised kidney function, it requires professional clinical interventions to treat the cause.