Diabetes (HTHSCI 2LA2)

Diabetes Mellitus

A heterogeneous metabolic disorder characterized by hyperglycemia due to impaired insulin secretion or action.

Type 2 DM

Characterized by hyperglycemia, insulin resistance, and relative insulin deficiency.

Type 1 DM

An autoimmune disorder resulting in the destruction of beta cells and absolute insulin deficiency.

Prevalence of Diabetes

Type 2 DM accounts for approximately 90% of diabetes cases.

Etiology of Type 1 DM

Autoimmune mediated specific loss of beta cells in the pancreatic islets Langerhans.

Autoimmune Type 1A

Autoimmune mediated specific loss of beta cells in the pancreatic islets Langerhans.

Genes

Inherited major histocompatibility complex (MHC) genes on chromosome 6 which encode leukocyte antigens HLA-DQ and HLA-DR.

Autoantibodies

Specific to beta cell destruction, including insulin autoantibodies, islet cell autoantibodies, and antibodies directed at other islet autoantigens.

Environmental factors

Linked to Type 1 DM, including drugs, chemicals, nutritional intake, and viruses.

Idiopathic Type 1B

Type 1 DM with no evidence of autoimmunity.

Etiology Type 2 DM

Characterized by hyperglycemia, insulin resistance, and relative insulin deficiency.

Metabolic syndrome

A cluster of cardiovascular disease risk factors related to insulin resistance.

Gestational Diabetes Mellitus

Any degree of glucose intolerance with onset or first recognition during pregnancy.

Glucose Metabolism

Efficient fuel that breaks down into CO2 and H2O when metabolized in the presence of oxygen.

Protein Metabolism

Amino acids are the building blocks of proteins and can be converted to fatty acids, ketones, or glucose for metabolic fuel.

Fat Metabolism

The most efficient form of fuel storage, with calories obtained from fat.

The Pancreas

Made up of exocrine and endocrine components, including beta cells that secrete insulin, alpha cells that secrete glucagon, and delta cells that secrete somatostatin.

Insulin

The hormone that lowers blood glucose levels by promoting glucose uptake, glycogen synthesis, and inhibiting gluconeogenesis.

Amylin

Released at the same time as insulin, regulates blood sugar by delaying nutrient uptake and has satiety and antihyperglycemic effects.

Glucagon

A hormone produced by alpha cells that works opposite to insulin by increasing blood sugar levels through glycogenolysis, gluconeogenesis, and lipolysis.

Somatostatin

Released by delta cells in the endocrine pancreas, inhibits the release of insulin and glucagon, and decreases GI activity.

Counter-Regulatory Hormones

Hormones that counteract the storage functions of insulin and regulate blood glucose levels during periods of fasting, exercise, and stress.

Complications

Acute complications include hypoglycemia, diabetic ketoacidosis, and hyperosmolar hyperglycemic nonketotic syndrome. Chronic complications include microvascular and macrovascular diseases.

Polydipsia

Excessive thirst due to intracellular dehydration from hyperglycemia.

Polyphagia

Excessive hunger, usually in Type 1 DM, resulting from cellular starvation and depletion of stores of carbs, fats, and proteins.

Blurred vision

Caused by exposure of the lens and retina to hypersmolar fluids.

Fatigue

Due to lowered plasma glucose, poor use of food, and sleep loss.

Polyuria

Excessive urination due to the amount of glucose filtered by the kidneys exceeding what can be reabsorbed.

Paresthesia

Dysfunction of peripheral nerves, often associated with peripheral vascular disease.

Hemoglobin A1C

Reflects average plasma glucose levels over the past 2 to 3 months and is used for screening chronic hyperglycemia and assessing therapy effectiveness.

Insulin Therapy

Required in Type 1 DM and may be required in Type 2 DM, administered by injection.

Antidiabetic Agents

Pharmacological agents used to treat diabetes, including biguanides, incretins, SGLT-2 inhibitors, insulin secretagogues, alpha-glucosidase inhibitors, and thiazolidinediones.

Patient Teaching

Education provided to patients on lifestyle, nutrition, medications, avoiding/recognizing complications, and equipment use.

Metformin

A biguanide that reduces hepatic glucose output and increases insulin sensitivity of the liver and peripheral tissues.

Incretins

Peptides released in the GI tract that increase insulin synthesis and secretion, including DPP-4 inhibitors and GLP-1 receptor agonists.

SGLT-2 inhibitors

Pharmacological agents that inhibit glucose reabsorption in the kidneys, leading to increased urinary glucose excretion.

Insulin secretagogues

Pharmacological agents that stimulate insulin secretion, including sulfonylureas and meglitinides.

Alpha-glucosidase inhibitors

Pharmacological agents that delay the digestion of carbohydrates in the small intestine, reducing postprandial hyperglycemia.

Thiazolidinediones

Pharmacological agents that modulate the activity of peroxisome proliferator-activated receptor gamma, improving insulin sensitivity.

Orlistat

A weight loss agent that inhibits the absorption of dietary fats.

Diagnostic Tests for DM

Include fasting plasma glucose, random blood glucose test, oral glucose tolerance test, glycated hemoglobin, capillary blood glucose monitoring, urine tests, genetic studies, and autoantibodies.