Normal Physiology of the Pancreas
The pancreas is an organ that produces digestive enzymes and is located behind the stomach.
- Inside the pancreas are cells called the islets of Langerhans. These cells secrete hormones that regulate the metabolism of carbohydrates, fats, and proteins.
- Beta cells are one type of hormone-secreting cells in the islets of Langerhans. The main function of beta cells is to produce insulin.
- Insulin binds with receptors throughout the body to signal the body to send glucose into the cell. Once the glucose is inside cells, the body can excrete the glucose.
(McCance & Huether, 2019)
Figure 8. Islets of Langerhans (Darling, 2016)
Alterations in Pancreatic Physiology
When specific genetic and environmental factors combine, the function of the Pancreas can be altered. These alterations can lead to insulin resistance and hyperglycemia which then leads to type 2 diabetes mellitus (DM). Genetic predisposition to type 2 DM may include inherited beta-cell dysfunction and insulin resistance (McCance & Huether, 2019).
Risk Factors for DM:
Parent or sibling have type 2 DM
American Indian or Alaskan Native
Obesity
Sedentary lifestyle
Hypertension
Smoking
Lack of a balanced and healthy diet
(McCance & Huether, 2019; Bellou, Belbasis, Tzoulaki, & Evangelos, 2018)
Figure 9. Pathophysiology of Diabetes Mellitus (Skyler et al., 2017)
Obesity is the major factor that contributes to insulin resistance via different mechanisms.
- Adipokines are hormones produced in adipose (fat) tissue. When these hormone levels are increased in the blood, production of insulin is decreased and insulin resistance increases (McCance & Huether, 2019).
- High levels of cholesterol and triglycerides interfere with insulin secretion and can cause beta-cell death (McCance & Huether, 2019).
- Obesity causes an increase of inflammatory cytokines which cause insulin resistance by depositing fat in the liver and muscles (Skylar et al., 2017).
When a patient develops insulin resistance, beta-cells can not produce enough insulin to support the needs of the body. Eventually, this leads to beta-cell and islet inflammation, and then eventually beta-cell death (Skylar et al., 2017).
- When the beta-cells cannot produce enough insulin, glucose uptake into the cell is decreased resulting in hyperglycemia.
- Dysfunction in the beta-cells leads to type 2 DM.
- In type 2 DM, beta-cell function progressively worsens over time, resulting in even further increased insulin resistance and hyperglycemia (Skylar et al., 2017).
- Type 2 DM effects 9.3% of adults in the United States (McCance & Huether, 2019)
Diagnostic Criteria for Type 2 DM
- HbA1c: ≥ 6.5%
- Fasting (≥ 8 hours) blood glucose: ≥126 mg/dL
- 2 hour plasma glucose: ≥ 200 mg/dL
- Random plasma glucose in a patient with classic symptoms of hyperglycemia: ≥ 200 mg/dL
(McCance & Huether, 2019)
Correct Diagnosis:
The correct diagnosis for J.S. is type 2 diabetes mellitus.
J.S. has a Hb A1c of 10% and a fasting blood glucose of 240 mg/dL. Both of these values fit in the diagnostic criteria for DM. The patient also has obesity, a lack of a balanced diet, and he is a smoker. These are all risk factors for DM. In J.S.’s case, obesity is probably the largest factor that led to the development of DM. J.S. also presents with other common signs and symptoms of DM such as: polydipsia, polyuria, delayed wound healing, tingling in his feet, and blurred vision.
(McCance & Huether, 2019)