Diabetes mellitus is a chronic disease that is becoming more prevalent worldwide. Diabetes causes high blood sugar, which is harmful to health.
As of 2015, 30.3 million people in the United States, or about 9.4 percent of the population, had diabetes. Unfortunately, more than 1 in 4 people with diabetes don’t know they have it. Having undiagnosed diabetes increases the risk of diabetes-related complications such as kidney disease, heart disease, amputations, and more.
Many people also have prediabetes, a condition where blood sugars are slightly elevated but not high enough to be considered diabetes. Having prediabetes is a significant risk factor for eventually developing type 2 diabetes.
The U.S. Centers for Disease Control (CDC) estimates that up to 30% of people with prediabetes will develop type 2 diabetes within five years of their prediabetes diagnosis.
The majority of people with diabetes have type 2, which typically affects older adults and can be related to multiple known risk factors, including race, weight, and lifestyle factors. Type 1 diabetes is rarer as it’s an autoimmune disorder. Type 1 usually occurs before age 18, so it’s also referred to as juvenile diabetes. Type 1 diabetes affects about 2-5% of the world’s population or about 1 in 300 American adults before the age of 18.
High blood sugar (hyperglycemia) isn’t a normal state, leading to many distinct symptoms as the body tries to rid itself of the extra blood sugar. One of the symptoms of high blood sugar is glycosuria or glucose in the urine.
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What is glycosuria?
Glycosuria is the term for sugar passing into the urine. While small amounts of sugar (glucose) in the urine can be normal, larger amounts are abnormal and often a symptom of an underlying health problem.
More than 15 mg/dL of glucose in the urine is considered abnormal. The most common cause of glycosuria is diabetes, as the body tries to rid itself of the elevated blood glucose levels through urination. Average blood sugars usually need to be around 180 mg/dL or higher for glycosuria to occur, but this threshold is different for each individual.
Glycosuria in nondiabetic patients having a euglycemic status is a sign of an impaired renal proximal tubular reabsorption of glucose
The kidneys are responsible for filtering waste and maintaining fluid and electrolyte balance. This waste is excreted in the form of urine, which flows from the kidneys to the bladder.
Normally, the kidneys will absorb small amounts of glucose into the renal tubules, which are parts of the kidneys. There is more glucose with elevated blood sugar levels than the renal tubules can absorb (the renal threshold for glucose), causing the sugar to “spillover” into the urine versus being absorbed by the kidney. Most of the excess glucose is absorbed by the proximal renal tubule, while the distal renal tubule absorbs a smaller amount.
What causes glycosuria?
The leading cause of glycosuria is elevated blood sugar levels from diabetes. Along with glycosuria, other symptoms of high blood sugar levels/diabetes include increased hunger, increased thirst, frequent urination, and unintentional weight loss.
Other causes of glycosuria include:
- Pregnancy and/or gestational diabetes: About 50% of pregnant women will experience glycosuria at some point. The rate at which the kidneys filter blood or the glomerular filtration rate (GFR) is increased during pregnancy. This can result in glucose being present in the urine even if blood sugar levels aren’t elevated (due to the increased filtration rate). In the case of gestational diabetes, glycosuria can be a sign of excess glucose. Renal glycosuria: Renal glycosuria is a rare condition where sugar is excreted in the urine despite normal blood sugar levels. Renal glycosuria is caused by improper functioning of the renal tubules and can cause no symptoms or severe side effects. It is usually an inherited condition, meaning it’s passed down through families, such as familial renal glycosuria.
- Interstitial nephritis: This disorder causes inflammation to the tubules in the kidneys, reducing the kidneys’ ability to filter blood. The result can be glucose “leaking” into the urine versus being reabsorbed. Interstitial nephritis can be caused by things such as infections, reactions to medications, imbalances of certain nutrients in the blood, and autoimmune conditions.
- SGLT2 inhibitor use: SGLT2 inhibitors are a newer class of drugs used to treat diabetes, including canagliflozin, dapagliflozin, and empagliflozin. They help to lower blood sugar by increasing the amount of glucose excreted by the kidneys, so they actually cause glycosuria.
Who is at risk?
Glycosuria is usually associated with diabetes, both type 1 diabetes and type 2 diabetes. Type 1 diabetes is much more rare than type 2 diabetes and is an autoimmune condition. Type 2 diabetes is the most common type of diabetes worldwide.
Risk factors for developing type 2 diabetes include:
- Weight: People who are considered overweight or obese according to their body mass index (BMI).
- Age: people 45 and older are at increased risk.
- Family history of diabetes
- Race/ethnicity: diabetes tends to affect certain races more than others. At-risk races include African American, Alaska Native, Native American, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander.
- High blood pressure: blood pressure higher than 120/80 increases risk.
- Altered lipid levels: low levels of HDL “good” cholesterol and high levels of LDL “bad” cholesterol are risk factors, as well as high triglycerides (blood fat).
- Pregnancy history: women with a history of gestational diabetes (GDM) or who gave birth to a baby 9 pounds or heavier are at increased risk.
- Physical activity: those who aren’t regularly active or who have a sedentary lifestyle are at increased risk.
- Smoking status: Smokers are 30-40% more likely to develop type 2 diabetes than nonsmokers.
- Health history: people with a history of heart attack or stroke have a higher likelihood of developing type 2 diabetes.
- PCOS: Polycystic Ovarian Syndrome (PCOS) in women is a risk factor, as it usually is associated with insulin resistance.
- Acanthosis nigricans: dark, velvety patches of skin are a sign of insulin resistance and are a risk factor for developing diabetes. These patches of skin usually occur around the neck or armpits.
Risk factors for type 1 diabetes are less understood since it’s an autoimmune condition. The known risk factors for type 1 diabetes include:
- Family history: people with a parent or sibling with type 1 diabetes are more likely to develop it than people without a family history.
- Genetics: certain genes tend to indicate an increased risk of type 1 diabetes.
- Geography: incidence of type 1 diabetes tends to increase as the distance from the equator increases.
- Age: the first peak of diagnosis tends to occur between ages 4-7, and again between ages 10-14.
Gestational diabetes (GDM) affects women during pregnancy. It occurs in women without a previous history of diabetes. The drastic shift in hormones during pregnancy can trigger insulin resistance, resulting in higher blood sugars. It typically goes away after pregnancy. Glycosuria can occur in a woman with GDM.
Risk factors for developing GDM include:
- Being at a higher weight when becoming pregnant.
- Being African-American, Asian, Hispanic, or Native American.
- Having a history of prediabetes or GDM.
- Having high blood pressure or other medical problems.
- Having given birth to a large baby weighing 9 pounds or more.
- Having given birth to a stillborn baby or one with birth defects.
- Being over the age of 25.
Chronic kidney disease can sometimes cause glycosuria, even in the absence of diabetes (nondiabetic glycosuria). Chronic kidney disease results in impaired kidney function and reduced glomerular filtration rate. Risk factors for developing chronic kidney disease include:
- High blood pressure
- Heart and blood vessel (cardiovascular) disease
- Being African-American, Native American, or Asian-American
- Family history of kidney disease
- Abnormal kidney structure
- Older age
What are the symptoms?
Glycosuria generally doesn’t have symptoms by itself, as it is a symptom of an underlying issue. People usually only find out they have glycosuria through a glucose urine test.
If undiagnosed and untreated, glycosuria may cause the following symptoms:
- extreme hunger
- extreme thirst or dehydration
- accidental urination
- more frequent urination
- nighttime urination
If glycosuria is due to problems with the tubules in the kidneys (such as interstitial nephritis), symptoms can include:
- Increased urine output
- Blood in your urine or dark urine
- Nausea or vomiting
- Fever or rash
- Elevated blood pressure
- Changes in mental status, such as drowsiness or confusion
- Swelling of any area of your body
- Sudden weight gain. This can be caused by extra fluid in the body.
If glycosuria is due to diabetes, some of the other symptoms can include:
- vision trouble
- minor cuts and abrasions that take a long time to heal
- unexplained weight loss
- darkening skin near armpits, neck, or other areas where the skin tends to fold
Glycosuria is diagnosed through a urine test and may be done in addition to blood glucose testing to determine if the glycosuria is related to elevated blood sugar levels. A normal urine glucose test is negative for glucose, or less than 15 mg/dL.
Normal fasting blood sugar levels for people without diabetes are less than 100 mg/dL, while normal post-meal (postprandial) blood sugars are less than 140 mg/dL for those without diabetes.
For people with diabetes, blood sugar targets are as follows per the American Diabetes Association (ADA), though these goals can vary individually.
If glycosuria is due to structural problems with the kidneys, other tests may be ordered to assess kidney function. Imaging tests such as CT scans and ultrasounds can be used to view the kidneys and determine if there are structural abnormalities or other problems. A renal biopsy may also be done if imaging studies show abnormalities of the kidneys.
Some kidney function tests commonly ordered include blood urea nitrogen (BUN), serum creatinine, and glomerular filtration rate (GFR).
How is it treated?
The most common cause of glycosuria is elevated blood sugar levels, so treatment is targeted at normalizing blood sugar. There are various approaches to diabetes management, including:
Healthy diet: Blood sugar levels can improve through eating a healthy diet, such as a Mediterranean diet or following the Plate Method.
A Mediterranean diet focuses on nutrient-dense foods and avoids refined sugars and red meat. A Mediterranean diet includes foods such as:
- Vegetables: Tomatoes, broccoli, kale, spinach, onions, cauliflower, carrots, Brussels sprouts, cucumbers, etc.
- Fruits: Apples, bananas, oranges, pears, strawberries, grapes, dates, figs, melons, peaches, etc.
- Nuts and seeds: Almonds, walnuts, macadamia nuts, hazelnuts, cashews, sunflower seeds, pumpkin seeds, etc.
- Legumes: Beans, peas, lentils, pulses, peanuts, chickpeas, etc.
- Tubers: Potatoes, sweet potatoes, turnips, yams, etc.
- Whole grains: Whole oats, brown rice, rye, barley, corn, buckwheat, whole wheat, whole-grain bread, and pasta.
- Fish and seafood: Salmon, sardines, trout, tuna, mackerel, shrimp, oysters, clams, crab, mussels, etc.
- Poultry: Chicken, duck, turkey, etc.
- Eggs: Chicken, quail, and duck eggs.
- Dairy: Cheese, yogurt, Greek yogurt, etc.
- Herbs and spices: Garlic, basil, mint, rosemary, sage, nutmeg, cinnamon, pepper, etc.
- Healthy Fats: Extra virgin olive oil, olives, avocados, and avocado oil.
Physical activity: 150 minutes per week of moderate to vigorous activity is recommended for people with and without diabetes. Strength or resistance training a few days per week is also recommended as it can help reduce insulin resistance by increasing the amount of glucose absorbed by the muscles to use as fuel.
Medications: For some people, lifestyle changes alone might not be enough to improve blood sugar levels. Needing medication isn’t a sign of failure but is a sign that the pancreas can’t produce enough insulin on its own to help lower blood sugars. Some of the more popular medications used to treat diabetes include:
- Metformin: Helps to reduce the amount of sugar released by the liver and improves insulin sensitivity.
- Sulfonylureas: Stimulate the pancreas to secrete more insulin.
- GLP1 receptor agonists: Promote insulin production, decrease glucose release from the liver, and slows stomach emptying to increase satiety.
- DPP-4 inhibitors: Promote insulin production, decrease glucagon (a hormone that increases your blood sugar level) production and delays gastric emptying.
- Insulin is available in different types: long-acting, short-acting, rapid-acting, intermediate-acting, and mixed. They differ in how quickly they take to work, how long until they are working the most to lower blood sugar and how long they last to provide blood sugar control.
People with type 1 diabetes are insulin-dependent and usually take at least two types of insulin on a daily basis or may use an insulin pump that delivers insulin on a continuous basis based on needs.
Glycosuria is the term for glucose being present in the urine, which is abnormal. The kidneys are organs that act to filter waste and other substances out of the blood. Once filtered, the waste and extra water are removed from the body in the form of urine. If the kidneys didn’t filter out enough glucose, glycosuria occurs.
Glycosuria is most often caused by diabetes but can also occur due to problems with the kidneys. Other blood tests and imaging studies can be done to determine the root cause of glycosuria.
Good diabetes management can help treat glycosuria, such as eating a healthy diet, being physically active, and taking medications as needed. Improving blood glucose is the best way to prevent and treat glycosuria, so most treatment for diabetic patients is geared towards that goal.