Diabetes is a chronic condition that affects how the body processes food into energy. When we eat, carbohydrates are broken down into glucose, a sugar that circulates in the bloodstream. The body’s cells need this glucose for fuel, but without proper regulation, high levels of blood sugar can lead to serious health issues.
Cells That Control Blood Sugar
The pancreas, an organ located behind the stomach, plays a central role in maintaining healthy blood glucose levels. Within the pancreas are specialized clusters of cells called the islets of Langerhans. These islets contain different types of cells, including beta cells and alpha cells, each with a distinct function in glucose regulation.
Beta cells produce insulin, a hormone that acts like a key, unlocking cell “doors” to allow glucose to enter for energy. When blood glucose levels rise after a meal, beta cells release insulin, signaling muscle, fat, and liver cells to absorb glucose from the bloodstream. This process helps lower blood sugar and provides cells with fuel.
Conversely, alpha cells in the pancreas produce glucagon, a hormone that has the opposite effect of insulin. When blood glucose levels drop too low, alpha cells release glucagon, signaling the liver to break down stored glycogen into glucose and release it into the bloodstream. Glucagon also stimulates the production of new glucose from non-carbohydrate sources in the liver, ensuring blood sugar levels remain stable even when food is not being consumed. The coordinated action of insulin and glucagon, along with other hormones, maintains blood glucose balance.
Cellular Changes in Type 1 Diabetes
Type 1 diabetes is an autoimmune condition where the body’s immune system mistakenly targets and destroys its own insulin-producing beta cells in the pancreas. This destructive process is mediated by autoreactive T cells, which incorrectly identify beta cells as threats and launch an attack.
This autoimmune attack results in a significant reduction or complete absence of insulin production. Without sufficient insulin, glucose cannot enter the body’s cells effectively, leading to a buildup of sugar in the bloodstream, known as hyperglycemia. Individuals with type 1 diabetes require lifelong insulin therapy to manage blood glucose levels and prevent serious complications.
Cellular Changes in Type 2 Diabetes
Type 2 diabetes involves different cellular issues, primarily characterized by insulin resistance and progressive beta cell dysfunction. Initially, cells in tissues such as muscles, fat, and the liver become less responsive to insulin’s signals. This means that even though the pancreas produces insulin, the “doors” do not open effectively, preventing glucose from entering the cells.
As cells become resistant to insulin, the pancreas attempts to compensate by producing more insulin. Over time, this increased demand can overwork the beta cells. This prolonged strain leads to beta cell dysfunction, causing a decline in their ability to produce enough insulin. This progressive failure, combined with ongoing insulin resistance, ultimately results in elevated blood glucose levels and a diagnosis of type 2 diabetes.
Widespread Cellular Effects of Diabetes
Prolonged high blood sugar, or hyperglycemia, resulting from the cellular dysfunctions in diabetes, can lead to widespread damage across various cell types and tissues throughout the body. This sustained elevation of glucose negatively impacts small blood vessels, contributing to complications in several organ systems.
In the eyes, high glucose levels can harm the tiny blood vessels in the retina, potentially leading to vision problems or blindness (retinopathy). Similarly, the delicate filtering units in the kidneys, which contain numerous small blood vessels, can become damaged, leading to nephropathy and potentially kidney failure. High blood sugar also affects the nerves, causing damage that can result in pain, numbness, or digestive issues (neuropathy). These complications are secondary consequences of uncontrolled glucose, affecting cells beyond those directly involved in glucose regulation.