Diabetes Mellitus (DM) commonly known as Diabetes is a group of metabolic disorders, sharing the underlying feature of an increase in blood sugar level, over a long period of time. It results either from defects in insulin secretion, insulin action, or both.
Classification of DM :
The vast majority of cases of Diabetes falls into two major categories –
- Type 1 Diabetes or Insulin-dependent Diabetes Mellitus (IDDM)
- Type 2 Diabetes or Non-Insulin dependent Diabetes Melltius (NIDDM)
Let us now learn what is Insulin and its role in glucose metabolism briefly:
Insulin is a peptide hormone released from Beta cells of pancreatic islets, in response to high blood glucose levels. It regulates the metabolism of carbohydrates, fats, and proteins by enhancing the absorption of glucose from the bloodstream into the target cells (liver, adipose tissue, skeletal muscle). Insulin binds to the receptors on the surface of the target cell. Insulin and its receptor first move to the inside of the cell, which activates glucose transporter channels to translocate to the membrane. These channels allow glucose to enter the cell. The cell can then use the glucose for metabolism, where it is oxidized to generate ATP.
Pathogenesis of Diabetes :
Type 1 Diabetes – This is characterized by “an absolute deficiency of insulin secretion” caused by pancreatic beta-cell destruction, usually resulting from an autoimmune response (the main immunological defect being the failure of self-tolerance in T-cells). Its pathogenesis represents the interplay of genetic susceptibility and environmental factors.
Type 2 Diabetes – This is caused by a “relative insulin deficiency” due to a combination of
peripheral resistance to insulin action and an inadequate compensatory response of insulin
secretion by the pancreatic β cells. Lifestyle factors including obesity, insufficient physical exercise, along with genetic factors play a pivotal role in the development of T2DM.
Signs and Symptoms
- Polydipsia (increased thirst)
- Polyuria (increased urination) and nocturia
- Polyphagia (increased hunger)
- Weight loss
- Fatigue, lethargy
- Blurring of vision
- Slow healing of cuts
- Mood changes
Symptoms of polydipsia, polyuria, nocturia, and rapid weight loss are prominent in type 1 diabetes but are often absent in patients with type 2 diabetes, many of whom are asymptomatic (hence the term ‘Silent Killer’ is more associated with T2DM).
Table showing the differences in clinical features between Type 1 DM and Type 2 DM
- Acute complications include Diabetic ketoacidosis (more common with Type1 DM) and hyperosmolar nonketotic coma (often with Type2 DM)
- Long-standing Diabetes may involve cardiovascular disease, diabetic retinopathy, neuropathy, nephropathy, foot ulcers.
The diagnosis of diabetes is established by elevation of blood glucose by any one of three criteria:
1. A random blood glucose concentration of 200 mg/dL or higher, with classical signs and symptoms.
2. A fasting glucose concentration of 126 mg/dL or higher on more than one occasion
3. An abnormal oral glucose tolerance test (OGTT), in which the glucose concentration is 200 mg/dL or higher 2 hours after a standard carbohydrate load (75 g of glucose).
There is no preventive measure for Type 1 DM. Type 2 DM which accounts for 90% of all cases worldwide, can be prevented by lifestyle changes like maintaining normal body weight, engaging in physical exercise, and a healthy diet. A diet rich in whole grains, fiber, polyunsaturated fats as found in nuts, should be embraced. The progression of prediabetes (impaired glucose tolerance) to Type 2 DM can also be delayed with the aforementioned dietary changes and weight loss.
The aims are to improve symptoms of hyperglycemia and minimize the risks of long-term microvascular and macrovascular complications.
Type 1 DM can only be treated with insulin, typically with a combination of regular and NPH insulin or synthetic insulin analogs.
In patients with type 2 diabetes, the first approach to management involves advice about dietary and lifestyle modification along with oral hypoglycaemic agents like metformin (1st line treatment for Type 2 DM).
“An ounce of prevention is worth a pound of cure”
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