High Blood Sugar: Main Causes and Health Risks

Elevated blood sugar (glucose) levels, or hyperglycemia, is a serious condition that can lead to numerous complications if left uncontrolled. Glucose is the primary source of energy for cells, but its excess has a destructive effect on the body. Understanding the causes of hyperglycemia is critical for prevention, timely diagnosis, and effective treatment. In this article, we will examine the main factors contributing to rising blood sugar levels and the associated risks.

Chronic Diseases as Key Factors

The most well-known and common cause of chronically elevated blood sugar is diabetes mellitus. There are several types of it:

• Type 1 Diabetes Mellitus: This is an autoimmune disease in which the body's immune system destroys the cells of the pancreas that produce insulin. As a result, the body cannot produce enough insulin, the hormone necessary for cells to absorb glucose.
• Type 2 Diabetes Mellitus: This type of diabetes is most commonly associated with insulin resistance, where the body's cells stop responding adequately to insulin. Over time, the pancreas may become depleted and produce less insulin. Risk factors include obesity, a sedentary lifestyle, and genetic predisposition.

Long-term elevation of glycated hemoglobin (HbA1c), which reflects the average blood sugar level over the past 2-3 months, in patients with diabetes significantly increases the risks of serious cardiovascular complications. For example, in people with diabetes and atrial fibrillation, a high HbA1c level (greater than 63 mmol/mol, which corresponds to approximately 7.9%) is associated with an increased risk of death, ischemic stroke, and myocardial infarction [1].

Metabolic Syndrome and Its Components

Metabolic syndrome is a complex of interconnected metabolic disorders that significantly increases the risk of developing type 2 diabetes mellitus, cardiovascular disease, and stroke. It is a powerful risk factor for adverse cardiovascular outcomes, including atrial fibrillation, especially in patients with chronic kidney disease [6]. Key components of metabolic syndrome include [6]:

• High blood pressure (hypertension).
• Excessive waist circumference (abdominal obesity).
• Elevated triglyceride levels (a type of fat in the blood). High triglycerides are a well-known marker of cardiovascular risk [2].
• Low "good" cholesterol (HDL) levels.
• Elevated fasting blood glucose levels or diagnosed diabetes.

The combination of these factors creates a favorable environment for the development of insulin resistance and, consequently, chronic hyperglycemia.

Stress Hyperglycemia: Temporary Blood Sugar Elevation

High blood sugar levels do not always indicate chronic diabetes. In some cases, glucose may temporarily rise in response to acute stress or severe illness. This phenomenon is called stress hyperglycemia (SH). It is frequently observed in patients without diabetes, especially in acute conditions such as acute decompensated heart failure (ADHF) [3].

Studies show that SH (random blood sugar levels above 140 mg/dL or 7.8 mmol/L) in non-diabetic patients with ADHF is significantly associated with an increased incidence of major adverse cardiovascular events (MACEs), including cardiac death, non-fatal myocardial infarction, and readmission for heart failure [3]. Risk factors for the development of SH include age over 65 years and a history of hospitalizations for heart failure [3].

Causes of stress hyperglycemia include:

• Acute infections and inflammatory processes.
• Trauma and surgical interventions.
• Myocardial infarction or stroke.
• Acute heart failure [3].
• Severe emotional stress.

In these situations, the body releases stress hormones (e.g., cortisol, adrenaline) that raise glucose levels to provide cells with the energy needed to combat stress.

Other Factors Affecting Glucose Levels

In addition to the main causes, there are other factors that can contribute to elevated blood sugar levels:

• Medications: Certain drugs, such as glucocorticosteroids, diuretics, beta-blockers, some antidepressants, and atypical antipsychotics, can affect glucose metabolism and cause hyperglycemia.
• Pancreatic Diseases: Chronic pancreatitis, cystic fibrosis, or pancreatic tumors can damage insulin-producing cells, leading to insulin deficiency.
• Hormonal Disorders: Conditions such as Cushing's syndrome (excess cortisol), acromegaly (excess growth hormone), or hyperthyroidism (excess thyroid hormones) can impair glucose regulation.
• Genetic Predisposition: Certain genetic mutations can predispose individuals to diabetes or other metabolic disorders, for example, familial hypertriglyceridemia associated with a pathogenic variant of the lipoprotein lipase gene [2].
• Sedentary Lifestyle and Poor Diet: A diet rich in fast carbohydrates and saturated fats, combined with a lack of physical activity, contributes to weight gain, the development of insulin resistance, and metabolic syndrome.
• Age: The risk of developing type 2 diabetes increases with age. Furthermore, diabetes significantly increases the risk of benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms in older men, which may be related to increased sympathetic tone, insulin-stimulated prostate growth, and systemic inflammation [5].

When Should You See a Doctor?

It is important not to ignore symptoms that may indicate elevated blood sugar levels. These include:

• Frequent urination.
• Increased thirst.
• Constant feeling of hunger.
• Unexplained weight loss.
• Increased fatigue.
• Blurred vision.
• Slow-healing wounds.
• Frequent infections.

Regular medical check-ups and blood glucose tests, especially when risk factors are present, allow for early problem detection and treatment initiation. Early diagnosis and blood sugar control help prevent serious complications such as cardiovascular disease [1, 3, 8], kidney, nerve, and eye damage.

Sources

1. Glycemic control and clinical outcomes in patients with diabetes and atrial fibrillation: a nationwide cohort study.
2. Case report: Severe hypertriglyceridemia and multivessel coronary artery disease – treatment and plaque characteristics.
3. Paradigm shift: how stress hyperglycemia is changing heart failure management approaches.
4. Diabetes and benign prostatic hyperplasia: emerging clinical links.
5. Metabolic syndrome and the risk of atrial fibrillation in chronic kidney disease.
6. Association between admission blood glucose levels and atypical angina in patients with coronary artery disease.

The information provided in the article is for informational purposes only and cannot replace the consultation of a qualified medical specialist. Always consult a physician for diagnosis and treatment.