What Causes Diabetes?

Diabetes mellitus is a metabolic disorder characterized by constant high levels of blood glucose (sugar) caused by the body’s inability to produce or utilize insulin, a hormone that is required to convert sugar and starches into energy. Insulin, a small protein, is secreted by beta cells in the pancreas primarily in response to elevated blood concentrations of glucose.

How glucose is regulated in the body: function of insulin

Intestines absorb carbohydrates (or sugars) into the bloodstream after a meal. Pancreas detects this increase and responds by secreting insulin. The amount of insulin secreted into the blood increases as the blood glucose rises. 

Insulin is a chemical messenger, who can “talk” to cells in the body that have built-in receivers for insulin’s messages. In response to insulin, the muscle, red blood cells, and fat cells absorb glucose out of the blood. When a cell has insulin attached to its surface, the cell is able to absorb glucose (sugar) from the blood stream for converting it into energy.

Insulin converts the excess glucose into glycogen and stores it in the liver and muscles. The excess blood sugar that cannot be stored as glycogen will be converted to fat and stored in the adipose tissue.

When the blood glucose falls (between meals, during exercise), the amount of insulin secreted by the pancreatic cells goes down. Severe insulin deficiency produces hyperglycaemia. The body cells starve, so the body starts looking for alternate sources of energy. Pancreas secretes another hormone called glucagon whenever the levels of glucose go down. Glucagon makes the liver release the glucose it has stored in its cells into the blood stream. It also induces the liver and muscle cells to make glucose.

The receptors are also found on the surface of liver as well as certain cells in the kidney and in the appetite control center of the brain. This control center in the brain coordinates metabolism through adjustment of the activities of the liver, kidneys, intestine and adipose tissue, controls appetite and coordinates it with energy utilization. 

Types of Diabetes

There are three main types of diabetes:

• Type 1 diabetes
• Type 2 diabetes
• Gestational diabetes

Type 1 Diabetes

Type 1 Diabetes is autoimmune disease that results from the destruction of beta cells in the pancreas. Some of the factors which may trigger type 1 diabetes may be genetic, poor diet and environment (virus affecting pancreas). Diabetes can also result from drugs that may cause abnormal secretion of some hormones in blood which act as antagonists to insulin. Steroids like cortisone, if taken for an extended period of time, can unduly increase blood glucose and strain the pancreas. Similarly women taking prolonged Estrogen Replacement Therapy may find their blood sugar shoot up.

Type 2 Diabetes

Type 2 Diabetes, a metabolic disorder, is found in people who eat carb-rich, high-glycemic diet. As a result, levels of sugar in the blood become elevated and the pancreas pumps in more insulin. Cells protect themselves from this onslaught of toxic insulin by reducing number of insulin receptors on them. This causes insulin levels to shoot. Elevated insulin dampens appetite and puts the body in a “storage mode” and converts protein, glucose, and dietary fat to stored fat. Increased demand on pancreas slows it down. Once the production of insulin starts slowing down, or the insulin resistance goes up, then blood sugar goes up and the person becomes a diabetic.

Gestational Diabetes

The hormones involved in development of placenta during pregnancy reduce a woman’s receptivity to insulin and cause insulin resistance. Glucose builds up in the blood leading to hyperglycemia.

It is important to take adequate care of gestational diabetes affects both the mother and the baby. Insulin does not cross the placenta, as glucose and other nutrients do. The baby’s blood glucose rises and the baby has to make extra insulin to get rid of the blood glucose. Since the baby gets more glucose than it needs, the extra glucose is stored as fat. At birth, the baby may be fat and develop breathing problems or may develop hypoglycemia due to over production of insulin.