Your Guide to Hyperglycemia (High Blood Sugar): Causes, Symptoms, Diagnosis, and Treatment Options

Hyperglycemia, or high blood sugar, is a prevalent health issue affecting millions worldwide. According to the International Diabetes Federation, approximately 537 million adults were living with diabetes (characterized by chronic elevations in high blood sugar) in 2021, and this number is expected to rise to 783 million by 2045. This is a prominent public health issue, as diabetes was the eighth leading cause of death in the United States in 2021 and attributed to total healthcare spending of nearly $413 billion in 2022 (42). 

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What Is Hyperglycemia?

Blood sugar, or glucose, is the primary energy source for the body's cells. It is derived from the breakdown of dietary carbohydrates and transported through the bloodstream. It is then absorbed by cells with the help of insulin, a hormone produced by the pancreas. 

Hyperglycemia occurs when there is an excessive amount of glucose in the blood. It happens when the body has too little insulin or stops responding to its signals properly (more on this later).

Blood sugar is measured in milligrams per deciliter (mg/dL). For people without diabetes, normal fasting (not eating for at least eight hours) blood sugar is 70-100 mg/dL. Blood sugar levels measured 1-2 hours after eating should be below 140 mg/dL. Blood sugar levels higher than this can indicate that you have prediabetes or diabetes. (23) 

What Are the Symptoms of Hyperglycemia?

Hyperglycemia usually doesn't cause symptoms until blood sugar levels are above 180-200 mg/dL. You should speak to your doctor if you begin to experience any of the following symptoms: 

• Frequent urination (polyuria)
• Increased thirst (polydipsia)
• Increased hunger (polyphagia)
• Blurred vision
• Headache
• Fatigue 

• Unintentional weight loss
• Poor wound healing
• Frequent infections
• Changes in skin appearance
• Neuropathy (numbness, pain, and tingling in the hands and feet)

Diabetic ketoacidosis (DKA) is a life-threatening condition that can occur when the body doesn't produce enough insulin to push blood sugar into the cells for energy. When this happens, the liver will break down fats, producing acidic molecules called ketones. While anyone with diabetes can develop DKA, it most commonly occurs as a complication of type 1 diabetes. DKA may be the first sign of diabetes in a patient who hasn't already been diagnosed. Patients who experience the following symptoms need to be evaluated by a doctor immediately: 

• Polydipsia and a very dry mouth
• Polyuria
• Fruity smelling breath
• Difficulty breathing
• Nausea, vomiting, and abdominal pain
• Fatigue
• Confusion
• Persistent blood sugar elevation above 300 mg/dL
• Moderate or high ketones in urine (measured with an over-the-counter test)

Hyperosmolar hyperglycemic state (HHS) is another life-threatening complication of diabetes. Very high blood sugar levels (usually higher than 600 mg/dL) cause severe dehydration and highly concentrated blood. Symptoms typically take days or weeks to develop and include: 

• Dry mouth and polydipsia
• Polyuria
• Changes in vision
• Weakness or paralysis 
• Confusion, delirium, and hallucinations
• Loss of consciousness

The main difference between HHS and DKA is that HHS mainly occurs in patients with type 2 diabetes and doesn't involve ketones (30).

What Are the Causes of Hyperglycemia?

Hyperglycemia is most commonly associated with diabetes. There are three classifications of diabetes:

• Type 1 diabetes is caused by an autoimmune response where the body's immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. This destruction leads to a deficiency of insulin. Without insulin, glucose cannot enter the cells and remains in the bloodstream, leading to high blood sugar levels.
• Type 1.5 diabetes, also known as latent autoimmune diabetes in adults (LADA), is caused by an autoimmune response that gradually destroys pancreatic beta cells. Unlike type 1 diabetes, which typically manifests in childhood, LADA develops more slowly and often presents in adulthood.
• Type 2 diabetes is primarily caused by insulin resistance, where the body's cells do not respond effectively to insulin, leading to elevated blood sugar levels. Over time, the pancreas compensates by producing more insulin, which can eventually lead to decreased insulin production. Contributing factors to insulin resistance include genetics, obesity, physical inactivity, and poor diet.

Hyperglycemia can occur in people without diabetes. This is called nondiabetic hyperglycemia. Examples of situations that increase blood sugar levels include:

• Critical illness or injury 
• Surgery
• Emotional stress
• Certain medications, such as corticosteroids, some blood pressure drugs, and antipsychotics
• Medical conditions, including cystic fibrosis, hemochromatosis, polycystic ovary syndrome (PCOS), and Cushing's syndrome

Lab Tests to Diagnose Hyperglycemia

Several laboratory tests are used to diagnose hyperglycemia:

Fasting Blood Glucose

This measures blood sugar after not eating for at least eight hours (46).  

• Normal: below 100 mg/dL
• Prediabetes: 100-125 mg/dL
• Diabetes: 126 mg/dL mg/dL or higher

Order fasting blood glucose through Rupa Health with one of the following tests:

• Glucose by Access Med Labs
• Glucose by Boston Heart Diagnostics

Oral Glucose Tolerance Test (OGTT)

This test measures your blood sugar before and after drinking a glucose-rich liquid. After fasting overnight, your fasting blood sugar level is measured, followed by additional measurements at 1 hour, 2 hours, and possibly 3 hours after drinking the liquid. (46) 

Results at 2 hours:

• Normal: 140 mg/dL or below
• Prediabetes: 140-199 mg/dL
• Diabetes: 200 mg/dL or higher

Hemoglobin A1c (HbA1c)

HbA1c reflects average blood glucose levels over the past 2-3 months.

• Normal: less than 5.7%
• Prediabetes: 5.7-6.4%
• Diabetes: 6.5% or higher

Order HbA1c through Rupa Health with one of the following tests:

• Hemoglobin A1c (HbA1c) by Boston Heart Diagnostics
• Hemoglobin A1c (HbA1c) by ZRT Laboratory
• Hemoglobin A1c by Access Med Labs

Additional Testing and Biomarkers

Additional tests can be ordered to complement the three above and create a more holistic evaluation of blood sugar control: 

Continuous glucose monitoring (CGM) is being utilized more commonly to provide real-time blood glucose readings throughout the day. CGMs are beneficial for understanding blood sugar trends and making real-time lifestyle and medication adjustments. 2022 guidelines from the American Diabetes Association (ADA) recommend using CGM to improve glucose control. 

A fructosamine test measures the average blood glucose levels over the past 2-3 weeks. It should be ordered when there is a need to evaluate blood sugar control over a shorter period than HbA1c testing. It is particularly useful for patients with conditions that affect red blood cell lifespan, such as anemia, which can distort HbA1c results. (25) 

Fasting insulin helps assess insulin resistance. Research has correlated fasting insulin levels over 7 mcIU/mL with increased future risk of metabolic syndrome and type II diabetes.

A C-peptide test indicates how much insulin the pancreas produces, helping differentiate between type 1 and type 2 diabetes. 

The presence of diabetes-associated autoantibodies, most commonly anti-glutamic acid decarboxylase 65 (GAD65) and islet-cell antibodies (ICA), is indicative of an autoimmune response against pancreatic beta cells. These antibodies are used to diagnose diabetes types 1 and 1.5 and differentiate them from type 2.

Given the negative toll chronic hyperglycemia has on cardiometabolic health, a lipid profile (which measures cholesterol and triglyceride levels) and a comprehensive metabolic panel (CMP) are recommended at regular intervals (28).  

How to Treat Hyperglycemia

Basic lifestyle habits can prevent unwanted blood sugar spikes:

• Blood sugar monitoring enables personalized blood sugar management by helping patients understand how different foods, activities, and medications affect their blood sugar levels. It also helps healthcare providers make informed decisions about treatment recommendations and modifications. Patients should follow their doctor's instructions on how to track their blood sugar levels. Typical times for blood sugar monitoring are when you wake up, before meals, two hours after meals, before and after exercise, and before bed. (5) 
• Studies show that regular exercise improves blood sugar levels and insulin resistance. The ADA recommends that adults with type 2 diabetes engage in aerobic and resistance exercise training, aiming for at least 150 minutes of physical activity weekly, and should decrease their daily sedentary behaviors. (15) 
• Because dietary carbohydrates are broken down into glucose, they are the primary driver of blood sugar levels. Therefore, eating a healthy diet and monitoring carbohydrate intake is essential for maintaining stable blood sugar levels. The ADA recommends the Diabetes Plate Method for balancing blood sugar. This method is a simple visual tool for managing portion sizes and promoting balanced meals, where half the plate is filled with non-starchy vegetables, a quarter with lean proteins, and the remaining quarter with complex carbohydrates (e.g., whole grains or starchy vegetables). 
• The natural stress response increases blood sugar levels because stress hormones, such as cortisol and adrenaline, stimulate the liver to release glucose into the bloodstream for immediate energy, which is necessary for the body's "fight-or-flight" reaction. Managing stress with various techniques, such as cognitive behavioral therapy, effectively lowers blood sugar levels. 

People diagnosed with diabetes may also require medications to bring blood sugar levels down into their goal range. These medications target various mechanisms contributing to hyperglycemia in diabetes, including insulin resistance, decreased insulin secretion, and increased glucose production by the liver. The choice of medication(s) used will be determined by the type of diabetes, degree of hyperglycemia, and response to therapy. (39) 

Severe hyperglycemia, such as in cases of DKA and HHS, requires immediate and emergency medical care. Both conditions require the intravenous administration of fluids for rehydration, electrolytes, and insulin. (30, 49) 

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Key Takeaways

• Hyperglycemia is a significant health concern that requires diligent management to prevent complications. 
• By understanding its symptoms and causes, individuals can take proactive steps to monitor and control their blood sugar levels to prevent hyperglycemic episodes. Immediate actions and long-term strategies are required to manage hyperglycemia effectively. 
• Medical practitioners are vital in educating and supporting patients in achieving optimal blood sugar control and improving their overall quality of life. 

Frequently Asked Questions (FAQs)

What Is Considered Hyperglycemia?

Hyperglycemia is defined as having higher-than-normal blood sugar levels. It is often associated with diabetes mellitus, which is caused by insulin deficiency or resistance.

What Are the First Signs of Hyperglycemia?

The first signs of hyperglycemia often include frequent urination (polyuria), increased thirst (polydipsia), and increased hunger (polyphagia) – collectively called "the 3 P's."

How Often Should Blood Sugar Levels Be Checked?

People with type 1 diabetes or those using insulin need to check their levels at least four times a day. Those with type 2 diabetes might check less frequently, such as before meals and bedtime or as advised by their healthcare provider. (3)

What Should I Do If I Experience Symptoms of Hyperglycemia?

If you experience symptoms of hyperglycemia, check your blood sugar levels immediately. Contact your healthcare provider for guidance, as they may need to adjust your medication regimen. If symptoms are severe or include signs of DKA or HHS, seek emergency medical attention.