Diabetes mellitus

Diabetes mellitus is a group of metabolic diseases characterized by increased levels of glucose in the blood (hyperglycemia) resulting from defects in insulin secretion, insulin action, or both. Normally, a certain amount of glucose circulates in the blood.

Insulin, a hormone produced by the pancreas, controls the level of glucose in the blood by regulating the production and storage of glucose.).

Insulin Transports and metabolizes glucose for energy Stimulates storage of glucose in the liver and muscle (in the form of glycogen) Signals the liver to stop the release of glucose Enhances storage of dietary fat in adipose tissue Accelerates transport of amino acids (derived from dietary protein) into cells Insulin also inhibits the breakdown of stored glucose, protein, and fat.

In diabetes, the cells may stop responding to insulin or the pancreas may stop producing insulin entirely. This leads to hyperglycemia, which may result in acute metabolic complications such as diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar nonketotic syndrome (HHNS

Long-term effects of hyperglycemia contribute to macrovascular complications (coronary artery disease, cerebrovascular disease, and peripheral vascular disease), chronic microvascular complications (kidney and eye disease), and neuropathic complications (diseases of the nerves).

The major classifications of diabetes are type 1 diabetes, type 2 diabetes, gestational diabetes ,and diabetes mellitus associated with other conditions or syndromes

In type 1 diabetes, the insulin-producing pancreatic beta cells are destroyed by an autoimmune process. As a result, patients produce little or no insulin and require insulin injections to control their blood glucose levels. Type 1 diabetes affects approximately 5% to 10% of people with the disease. Type 1 diabetes is characterized by an acute onset, usually before 30 years of age

In type 2 diabetes, people have decreased sensitivity to insulin (called insulin resistance) and impaired beta cell functioning resulting in decreased insulin production. Type 2 diabetes affects approximately 90% to 95% of people with the disease .It occurs more commonly among people who are older than 30 years of age and obese

Initially, type 2 diabetes is treated with diet and exercise Initially, type 2 diabetes is treated with diet and exercise. If elevated glucose levels persist, diet and exercise are supplemented with oral antidiabetic agents. In some people with type 2 diabetes, oral agents do not control hyperglycemia, and insulin injections are required.

Type 1 Diabetes Type 1 diabetes is characterized by destruction of the pancreatic beta cells. Combined genetic, immunologic, and possibly environmental (eg, viral) factors are thought to contribute to beta cell destruction. Although the events that lead to beta cell destruction are not fully understood, it is generally accepted that a genetic susceptibility is a common underlying factor in the development of type 1 diabetes

This genetic tendency has been found in people with certain human leukocyte antigen (HLA) types. HLA refers to a cluster of genes responsible for transplantation antigens and other immune processes diabetes commonly develops during childhood and adolescence, but it can occur at any age .

Regardless of the specific cause, the destruction of the beta cells results in : decreased insulin production unchecked glucose production by the liver, and fasting hyperglycemia. In addition, glucose derived from food cannot be stored in the liver .

Because insulin normally inhibits glycogenolysis (breakdown of stored glucose) and gluconeogenesis (production of new glucose from amino acids and other substrates), these processes contribute further to hyperglycemia. In addition, fat breakdown occurs, resulting in an increased production of ketone bodies, which are the byproducts of fat breakdown

Type 2 Diabetes The two main problems related to insulin in type 2 diabetes are insulin resistance and impaired insulin secretion. Insulin resistance refers to a decreased tissue sensitivity to insulin. Normally, insulin binds to special receptors on cell surfaces and initiates a series of reactions involved in glucose metabolism. In type 2 diabetes, these intracellular reactions are diminished, making insulin less effective at stimulating glucose uptake by the tissues and at regulating glucose release by the liver.

Despite the impaired insulin secretion that is characteristic of type 2 diabetes, there is enough insulin present to prevent the breakdown of fat and the accompanying production of ketone bodies. Therefore, DKA does not typically occur in type 2 diabetes. However, uncontrolled type 2 diabetes may lead to another acute problem—HHNS

For most patients (approximately 75%), type 2 diabetes is detected incidentally (eg, when routine laboratory tests or ophthalmoscopic examinations are performed). One consequence of undetected diabetes is that long-term diabetes complications (eg, eye disease, peripheral neuropathy, peripheral vascular disease) may have developed before the actual diagnosis of diabetes is made .

Clinical Manifestations Clinical manifestations depend on the patient's level of hyperglycemia. Classic clinical manifestations of all types of diabetes include the “three Ps”: polyuria, polydipsia, and polyphagia. Polyuria (increased urination) polydipsia (increased thirst) occur as a result of the excess loss of fluid associated with osmotic diuresis.

polyphagia (increased appetite) resulting from the catabolic state induced by insulin deficiency and the breakdown of proteins and fats.

Other symptoms include fatigue and weakness, sudden vision changes, tingling or numbness in hands or feet, dry skin, skin lesions or wounds that are slow to heal, and recurrent infections. The onset of type 1 diabetes may also be associated with sudden weight loss or nausea, vomiting, or abdominal pains, if DKA has developed.

Assessment and Diagnostic Findings 1. Symptoms of diabetes plus casual random plasma glucose concentration equal to or greater than 200 mg/dL (11.1 mmol/L).Casual is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss.

Fasting plasma glucose(FPS) greater than or equal to 126 mg/dL (7 Fasting plasma glucose(FPS) greater than or equal to 126 mg/dL (7.0 mmol/L). Fasting is defined as no caloric intake for at least 8 hours

Laboratory Examination HgbA1C (A1C) Fasting lipid profile Test for microalbuminuria Serum creatinine level Urinalysis Electrocardiogram

Overall Management of Diabetes The main goal of diabetes treatment is to normalize insulin activity and blood glucose levels to reduce the development of vascular and neuropathic complications normal blood glucose levels (euglycemia) without hypoglycemia while maintaining a high quality of life.

Diabetes management has five components: Nutritional therapy Exercise Monitoring Pharmacologic therapy Education

Nutritional Therapy Nutrition, meal planning, and weight control are the foundation of diabetes management. The most important objectives in the dietary and nutritional management of diabetes are: 1-control of total caloric intake to attain or maintain a reasonable body weight 2-control of blood glucose levels 3-normalization of lipids and blood pressure to prevent heart disease.

Exercise Exercise is extremely important in diabetes management because of its effects on lowering blood glucose and reducing cardiovascular risk factors. Exercise lowers blood glucose levels by increasing the uptake of glucose by body muscles and by improving insulin utilization. It also improves circulation and muscle tone.

Oral Antidiabetic Agents Sulfonylureas First-Generation Sulfonylureas Stimulate beta cells of the pancreas to secrete insulin; may improve binding between insulin and insulin receptors or increase the number of insulin receptors Used in type 2 diabetes to control blood glucose levels e.g Glimepiride (Amaryl)

Second-Generation Sulfonylureas Have more potent effects than first- generation sulfonylureas May be used in combination with metformin or insulin to improve glucose control .

Metformin (Glucophase): Inhibit production of glucose by the liver Increase body tissues' sensitivity to insulin Decrease hepatic synthesis of cholesterol Used in type 2 diabetes to control blood glucose levels