Glycosuria: Causes, Symptoms, and Treatment

Glycosuria is the presence of sugars in the urine, typically indicating an underlying issue with sugar metabolism. Glucosuria—the excretion of glucose in the urine—is the most common form. However, other sugars like lactose, fructose, galactose, and xylose may also appear, especially in specific metabolic disorders. Lactose in the urine is more common during pregnancy, whereas the presence of other sugars can suggest different metabolic conditions. Glycosuria is often detected through urinalysis and may signal issues like diabetes or kidney dysfunction.¹ Liman MNP, Jialal I. Physiology, Glycosuria. [Updated 2023 Mar 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557441/

What is Glucosuria?

Glucosuria refers to the presence of glucose in urine. It occurs when glucose filtered by the kidneys exceeds the kidney’s absorption capacity, so extra glucose is excreted into the urine, resulting in glucosuria. In normal individuals, glucose is present in small amounts, up to 25 mg/dl. Abnormal glucosuria (glucose levels above 25 mg/dl in fresh urine) can be due to high blood sugar, impaired kidney glucose absorption, or both.²Cowart SL, Stachura ME. Glucosuria. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 139. Available from: https://www.ncbi.nlm.nih.gov/books/NBK245/³Ferrannini E. Learning from glycosuria. Diabetes. 2011 Mar;60(3):695-6.

How do you Diagnose Glycosuria?

Glycosuria can be diagnosed via urine analysis. This involves dipping a test strip in a urine sample. The sample is then sent to a lab technician. The Lab technician can determine if your urine’s glucose levels indicate glycosuria. Glucose testing must be done with glucose-specific strips. This is because crossreactivity with other reducing sugars may occur, resulting in false positives.⁴McCowen KC, Smith RJ. Diabetes Mellitus: Classification and Chemical Pathology. Encyclopedia of Human Nutrition. Published online 2013:17-24. doi:https://doi.org/10.1016/b978-0-12-375083-9.00072-6

Based on the findings, other tests may be ordered to find the cause of Glycosuria. These may include blood tests such as fasting blood sugar or HbA1c to test for diabetes. Doctors can prescribe pregnant women the “Glucose Challenge test” or the “Oral Glucose Tolerance test” to rule out Gestational diabetes. Healthcare providers typically perform Gestational Diabetes testing between 24 and 28 weeks of pregnancy.

What are the Causes of Glycosuria?

Glycosuria is caused by conditions affecting blood glucose levels. However, the causes of glycosuria can be divided into three main categories:

• Sugar intake that is higher than the body can process. For example, ‘alimentary glycosuria’ occurs in normal individuals who have consumed excess carbohydrates.
• Kidney defects, such as renal tubular damage, impair sugar absorption.
• Problems with the production or utilization of insulin by the pancreas. Insulin is a hormone essential for controlling and regulating blood glucose levels. When there is less insulin production in the body or insulin is not functioning properly on cells (resistant to function), it leads to glucosuria.

Glycosuria & Pregnancy

The body produces hormones like Human Placental Lactogen (HPL) during pregnancy. These hormones help sustain the pregnancy. However, they also lead to insulin resistance. When your pancreas cannot produce additional insulin to overcome the resistance, it leads to Gestational Diabetes Mellitus(GDM).⁵ Johns Hopkins Medicine. Gestational Diabetes Mellitus (GDM). Johns Hopkins Medicine. Published 2019. https://www.hopkinsmedicine.org/health/conditions-and-diseases/diabetes/gestational-diabetes If insulin resistance becomes too strong, it can lead to high blood sugar levels.
Blood sugar levels normalize after the birth of the baby. However, 50% of women who had GDM go on to develop Type 2 diabetes.⁶CDC. Gestational Diabetes. Centers for Disease Control and Prevention. Published August 10, 2021. https://www.cdc.gov/diabetes/basics/gestational.html One of the signs of GDM is glycosuria, where excess glucose appears in the urine. Although some glycosuria can be normal during pregnancy due to increased renal glucose filtration, persistent or high levels may indicate GDM. It can lead to obese babies, hence necessitating a C-section. Moreover, the baby also has a higher risk of developing diabetes. Physicians can prescribe exercise, special diets, and insulin injections for treating GDM.

Diabetes & Glycosuria

Diabetes, also known as diabetes mellitus, is a condition where your body can’t produce sufficient insulin or use available insulin effectively. Without enough insulin, cells do not take up the glucose in the blood. This leads to a rise in blood sugar levels. As the kidneys cannot filter and reabsorb the excess glucose, it is excreted in the urine. Untreated diabetes may lead to retinopathy, neuropathy, gastropathy, cardiovascular complications, and nephropathy. Kidney damage due to diabetes (Diabetic nephropathy) may lead to proteinuria. Proteinuria is the presence of too much protein in urine. There are two main types of diabetes:

Type 1 Diabetes:

Type 1 diabetes is an autoimmune disease where the body’s immune system attacks and destroys the insulin-producing beta cells in the pancreas. It typically develops in childhood or adolescence. Type 1 requires insulin injections for treatment.

Type 2 Diabetes:

In this type, the body becomes resistant to insulin, leading to difficulty in using glucose properly. Obesity and weight gain are significant risk factors for type 2 diabetes. It often occurs later in life but can also affect obese children. Type 2 may be treated either with exercise, dietary modifications, anti-diabetic drugs, insulin, or both.

Fanconi Syndrome

Fanconi syndrome is a disorder affecting the proximal tubule of the kidney, resulting in the impaired absorption of various electrolytes and substances. It can be either inherited or acquired. In most cases, adults develop the acquired form of Fanconi syndrome, while children tend to experience the genetic variant.
Elevated levels of glucose, amino acids, and phosphates in urine can diagnose Fanconi syndrome (FS). FS may be accompanied by symptoms like bone pain, muscle weakness, dehydration, and electrolyte imbalances.

Renal Glycosuria

Renal glycosuria refers to glucose excretion in urine, even with normal or low blood glucose levels. Individuals with healthy kidney function excrete glucose in the urine only when their blood glucose levels are unusually high. However, individuals with renal glycosuria experience elevated glucose levels in urine due to a renal tubular defect.⁷KHACHADURIAN AK, KHACHADURIAN LA. THE INHERITANCE OF RENAL GLYCOSURIA. Am J Hum Genet. 1964;16(2):189-194. The condition may be acquired or inherited. Most cases are asymptomatic.

What are the Symptoms of Glycosuria?

Mild Glycosuria may not present with symptoms in many individuals. For example, pregnant women with GDM have glycosuria but don’t typically show symptoms. However, excess loss of glucose may present with symptoms ranging from:

• Excessive thirst
• Extreme Hunger
• Frequent urination and Dehydration

If glycosuria is due to diabetes, then there may be classical symptoms⁸Centers for Disease Control and Prevention. Diabetes Symptoms. CDC. Published 2022. https://www.cdc.gov/diabetes/basics/symptoms.html of diabetes like:

• Darkened patches of skin, especially in skin folds, and creases such as the neck, armpits, and groin
• Weight loss without trying
• Delayed wound healing
• Frequent infections

What are Glycosuria Treatments?

Glycosuria can be treated by treating the underlying condition. Renal glycosuria doesn’t need treatment. Treatment for Fanconi syndrome involves oral supplements, diet modifications, or IV infusions to restore electrolyte levels. Treating glycosuria due to GDM or diabetes requires:

• Regular exercise
• Specialized diet plans focusing on decreasing sugar and fat intake.
• Medications like metformin, gliclazide, SGLT2 inhibitors (gliflozins), and sulphonylureas are used to treat diabetes.
• Insulin injections

These treatments need consultation with your physician for a treatment plan and may require regular blood sugar testing.

Conclusion

Glycosuria is the presence of reducing sugars in urine. The most common type of glycosuria is glucosuria. GLucosuria is when excess glucose in the urine results from high blood sugar or impaired kidney function. Diagnosis involves urinalysis with glucose-specific strips. Causes include dietary sugar intake, kidney issues, and insulin problems. Pregnancy can lead to gestational diabetes, causing glycosuria. Diabetes, including Type 1 (autoimmune) and Type 2 (insulin resistance), can also result in glycosuria. Fanconi Syndrome is a disorder that affects electrolyte absorption and may lead to glycosuria. Renal glycosuria involves glucose in the urine despite normal blood glucose levels, often due to renal tubular defects. Symptoms may include excessive thirst, hunger, and frequent urination. Treatment depends on the underlying cause and may involve exercise, diet modification, medications, or insulin.

Refrences

• 1
  Liman MNP, Jialal I. Physiology, Glycosuria. [Updated 2023 Mar 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557441/
• 2
  Cowart SL, Stachura ME. Glucosuria. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 139. Available from: https://www.ncbi.nlm.nih.gov/books/NBK245/
• 3
  Ferrannini E. Learning from glycosuria. Diabetes. 2011 Mar;60(3):695-6.
• 4
  McCowen KC, Smith RJ. Diabetes Mellitus: Classification and Chemical Pathology. Encyclopedia of Human Nutrition. Published online 2013:17-24. doi:https://doi.org/10.1016/b978-0-12-375083-9.00072-6
• 5
  Johns Hopkins Medicine. Gestational Diabetes Mellitus (GDM). Johns Hopkins Medicine. Published 2019. https://www.hopkinsmedicine.org/health/conditions-and-diseases/diabetes/gestational-diabetes
• 6
  CDC. Gestational Diabetes. Centers for Disease Control and Prevention. Published August 10, 2021. https://www.cdc.gov/diabetes/basics/gestational.html
• 7
  KHACHADURIAN AK, KHACHADURIAN LA. THE INHERITANCE OF RENAL GLYCOSURIA. Am J Hum Genet. 1964;16(2):189-194.
• 8
  Centers for Disease Control and Prevention. Diabetes Symptoms. CDC. Published 2022. https://www.cdc.gov/diabetes/basics/symptoms.html