Type 2 diabetes mellitus is a chronic metabolic disorder where the body cannot properly use sugar, or glucose, for fuel. This condition develops when the body’s cells become resistant to insulin, a hormone that helps glucose enter cells, and the pancreas eventually cannot produce enough insulin to compensate. As a result, glucose accumulates in the bloodstream instead of being used for energy. This form accounts for 85-90% of diabetes cases and, while common in adults over 45, is increasingly seen in younger populations.
Causes and Risk Factors
The development of type 2 diabetes is centered on insulin resistance, where cells in muscle, fat, and the liver become less sensitive to insulin. Initially, the pancreas compensates by increasing insulin production to keep blood glucose levels stable. Over time, the insulin-producing cells in the pancreas wear down and can no longer produce enough of the hormone, leading to elevated blood sugar.
A person’s susceptibility is influenced by a combination of factors. Non-modifiable risks include genetics, a family history of the condition, and being over the age of 45. Certain ethnic backgrounds, including African American, Hispanic/Latino, American Indian, and Asian American, are also associated with a higher prevalence.
Other risk factors are linked to lifestyle and can be modified. These include:
- Being overweight or having obesity, as excess body fat increases insulin resistance.
- Physical inactivity, as regular exercise improves insulin sensitivity.
- Poor dietary habits.
- High blood pressure.
- Abnormal cholesterol levels.
The presence of these factors can lead to prediabetes, where blood sugar is high but not yet at the level of a diabetes diagnosis.
Symptoms and Diagnosis
The onset of type 2 diabetes symptoms is often gradual, developing over several years, and can be subtle enough to go unnoticed. Because many people are asymptomatic in the early stages, routine screening is important for at-risk individuals. Common indicators include:
- Increased thirst and frequent urination.
- Persistent hunger.
- Unexplained weight loss.
- A general sense of fatigue.
- Blurred vision.
- Slow-healing sores.
- Tingling and numbness in the hands or feet.
The primary diagnostic tool is the Hemoglobin A1c (HbA1c) test, which measures the average blood sugar level over the past two to three months. An A1c level of 6.5% or higher on two separate tests indicates diabetes.
Another method is the Fasting Plasma Glucose (FPG) test, which measures blood sugar after an overnight fast; a level of 126 mg/dL or higher on two occasions results in a diagnosis. The Oral Glucose Tolerance Test (OGTT) is also used, assessing how the body processes glucose by testing blood sugar before and two hours after a sugary drink.
Management of Type 2 Diabetes
Managing type 2 diabetes involves an individualized plan focused on lifestyle modification. Dietary strategies include counting carbohydrates or using the “plate method” to control portions and ensure a balanced intake of vegetables, proteins, and carbohydrates. The goal is to maintain stable blood glucose and a healthy weight.
Regular physical activity improves the body’s sensitivity to insulin, helping cells use glucose more effectively. The recommendation is at least 150 minutes of moderate-intensity aerobic exercise per week, complemented by muscle-strengthening activities. These lifestyle adjustments work together to lower blood sugar.
Consistent monitoring of blood glucose levels is a practice for many with type 2 diabetes. Using a glucose meter at home helps individuals and their healthcare providers understand how diet, exercise, and medication affect their levels. This data informs adjustments to the management plan to keep glucose within a target range.
When lifestyle changes are not enough to control blood sugar, medication becomes necessary. The most common first-line oral medication is metformin, which reduces glucose production in the liver and improves insulin sensitivity. If more is needed, other oral or injectable medications may be added, such as GLP-1 receptor agonists or SGLT2 inhibitors. In some cases, insulin injections are required to maintain glucose control.
Long-Term Health Complications
Chronically high blood sugar levels can damage various systems throughout the body, primarily by harming both large and small blood vessels. This damage can lead to a range of serious health problems. Managing blood sugar, blood pressure, and cholesterol is the primary focus to mitigate the risk of these issues.
The cardiovascular system is highly affected. Type 2 diabetes increases the risk of heart disease and stroke, as high glucose contributes to the narrowing and hardening of arteries (atherosclerosis). This condition can impair blood flow and lead to heart attacks or other cardiovascular events.
Damage to small blood vessels can affect the kidneys, leading to diabetic nephropathy. This condition impairs the kidneys’ ability to filter waste from the blood and can lead to kidney failure. Another complication is neuropathy, or nerve damage, which often affects the feet and legs, causing pain or a loss of sensation that can lead to unnoticed injuries and infections.
The eyes are also susceptible to damage, a condition called diabetic retinopathy, where high blood sugar harms the blood vessels in the retina. This can result in vision problems and may lead to blindness if untreated. Regular eye exams are necessary to detect and manage retinopathy early.