Diabetes Mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia, meaning high levels of glucose (sugar) in the blood. This occurs either because the pancreas does not produce enough insulin, or because the body’s cells do not respond properly to the insulin that is produced, or both.

Insulin is a hormone produced by the beta cells of the pancreas that is essential for allowing glucose to enter cells to be used for energy. When insulin is deficient or ineffective, glucose builds up in the bloodstream, leading to various short-term and long-term health complications affecting many organ systems.

Types of Diabetes Mellitus

Diabetes Mellitus is primarily classified into several main types:

1. Type 1 Diabetes Mellitus (T1DM): Previously known as insulin-dependent diabetes or juvenile diabetes.

2. Type 2 Diabetes Mellitus (T2DM): Previously known as non-insulin-dependent diabetes or adult-onset diabetes.

3. Gestational Diabetes Mellitus (GDM): Diabetes that occurs during pregnancy.

4. Other Specific Types of Diabetes: Less common forms caused by genetic defects, diseases of the pancreas (e.g., pancreatitis, cystic fibrosis), endocrine disorders (e.g., Cushing’s syndrome), or medications.

Type 1 Diabetes Mellitus (T1DM)

T1DM is an autoimmune disease in which the body’s immune system mistakenly attacks and destroys the beta cells in the pancreas that produce insulin. This leads to an absolute deficiency of insulin. T1DM typically develops in childhood or adolescence but can occur at any age.

Pathophysiology of T1DM:

The destruction of beta cells is a gradual process, but symptoms usually appear suddenly when a critical mass of beta cells (typically 80-90%) has been destroyed. Without insulin, glucose cannot enter the cells for energy, so it accumulates in the blood (hyperglycemia). The body starts breaking down fat and muscle for energy, leading to weight loss. The excess glucose in the blood spills into the urine (glucosuria), pulling water with it (osmotic diuresis), causing increased urination (polyuria) and excessive thirst (polydipsia). Because cells are starved for glucose, the individual experiences increased hunger (polyphagia). The breakdown of fats for energy produces ketones, which can build up in the blood and urine, leading to diabetic ketoacidosis (DKA), a life-threatening complication.

Type 2 Diabetes Mellitus (T2DM)

T2DM is the most common type, accounting for about 90-95% of all cases. It is characterized by a combination of insulin resistance (cells do not respond effectively to insulin) and a relative deficiency of insulin (the pancreas may initially produce more insulin to compensate, but over time, its ability to produce enough insulin declines). T2DM is strongly associated with obesity, physical inactivity, and genetics. It typically develops in adulthood but is increasingly seen in children and adolescents.

Pathophysiology of T2DM:

Insulin resistance means that the body’s cells (muscle, fat, and liver) do not take up glucose efficiently in response to insulin. The pancreas initially tries to overcome this resistance by producing more insulin (hyperinsulinemia). However, over time, the beta cells become exhausted and lose their ability to produce enough insulin to keep blood glucose levels normal. This leads to progressive hyperglycemia. The impaired insulin action also affects the liver, leading to increased glucose production. Unlike T1DM, DKA is less common in T2DM because there is usually enough insulin to prevent the excessive breakdown of fats and ketone production. However, T2DM patients are at risk for Hyperosmolar Hyperglycemic State (HHS), another serious complication.

Gestational Diabetes Mellitus (GDM)

GDM is a type of diabetes that develops during pregnancy in women who have not previously had diabetes. It is caused by hormonal changes during pregnancy that lead to insulin resistance. GDM usually occurs in the second or third trimester and typically resolves after delivery. However, women who have had GDM are at increased risk of developing T2DM later in life.

Pathophysiology of GDM:

Placental hormones (such as human placental lactogen, estrogen, progesterone, and cortisol) increase insulin resistance in the mother’s body to ensure enough glucose is available for the growing fetus. In most pregnancies, the mother’s pancreas can produce enough extra insulin to overcome this resistance and maintain normal blood glucose levels. However, in GDM, the pancreas cannot produce enough insulin to compensate, leading to hyperglycemia.

Risk Factors

• Type 1 DM: Family history of T1DM, genetics, exposure to certain viral infections, geographical factors.

• Type 2 DM: Obesity, physical inactivity, unhealthy diet, family history of T2DM, age (over 45), race/ethnicity (higher risk in African Americans, Hispanic/Latino Americans, American Indians, Asian Americans, Pacific Islanders), history of gestational diabetes, polycystic ovary syndrome (PCOS), history of heart disease or stroke.

• Gestational DM: History of GDM in a previous pregnancy, history of delivering a large baby (>9 lbs), obesity, family history of T2DM, certain ethnicities.

Signs and Symptoms

Symptoms of diabetes, especially T2DM, can develop gradually and may be mild or even absent in the early stages. The classic symptoms of hyperglycemia are often referred to as the “3 Ps”:

• Polyuria: Increased urination. This occurs because high blood glucose levels overwhelm the kidneys’ ability to reabsorb glucose, causing glucose to spill into the urine and draw water with it.

• Polydipsia: Increased thirst. This is a result of the excessive fluid loss from polyuria.

• Polyphagia: Increased hunger. Despite high blood glucose, cells are starved for energy because glucose cannot enter them effectively.

Other common symptoms include:

• Unexplained weight loss (more common in T1DM).

• Fatigue and weakness.

• Blurred vision (due to fluid shifts in the eye lens).

• Slow-healing sores or infections.

• Numbness or tingling in the hands or feet (sign of nerve damage – neuropathy).

• Dry, itchy skin.

• Recurrent infections (e.g., yeast infections, UTIs).

In T1DM, symptoms often appear suddenly and may include nausea, vomiting, and abdominal pain, which can be signs of DKA. T2DM may be diagnosed incidentally during routine blood tests before symptoms become noticeable.

Diagnosis

Diabetes is diagnosed based on blood glucose levels. Several tests can be used:

1. Fasting Plasma Glucose (FPG) Test: Measures blood glucose after an overnight fast (at least 8 hours).

   • Normal: < 100 mg/dL (< 5.6 mmol/L)

   • Prediabetes: 100-125 mg/dL (5.6-6.9 mmol/L)

   • Diabetes: $\ge$ 126 mg/dL ($\ge$ 7.0 mmol/L) on two separate occasions.

2. Oral Glucose Tolerance Test (OGTT): Measures blood glucose levels before and 2 hours after drinking a sugary liquid. Used to diagnose GDM and can also be used for T1DM and T2DM.

   • Normal (2-hour post-load): < 140 mg/dL (< 7.8 mmol/L)

   • Prediabetes (Impaired Glucose Tolerance): 140-199 mg/dL (7.8-11.0 mmol/L)

   • Diabetes (2-hour post-load): $\ge$ 200 mg/dL ($\ge$ 11.1 mmol/L)

3. Random Plasma Glucose Test: Measures blood glucose at any time of day, without regard to the last meal.

   • Diabetes: $\ge$ 200 mg/dL ($\ge$ 11.1 mmol/L) in a person with classic symptoms of hyperglycemia.

4. Hemoglobin A1c (HbA1c) Test: Measures the average blood glucose level over the past 2-3 months. It reflects how much glucose is attached to hemoglobin in red blood cells.

   • Normal: < 5.7%

   • Prediabetes: 5.7% – 6.4%

   • Diabetes: $\ge$ 6.5% on two separate occasions.

Additional tests may be done to differentiate between T1DM and T2DM, such as testing for autoantibodies (e.g., GAD antibodies, islet cell antibodies) which are present in T1DM but not T2DM, and measuring C-peptide levels (a marker of insulin production).

Management

The goals of diabetes management are to maintain blood glucose levels within a target range to prevent acute complications (DKA, HHS, hypoglycemia) and reduce the risk of long-term complications, while also managing cardiovascular risk factors. Management is individualized based on the type of diabetes, age, overall health, and lifestyle.

• Lifestyle Modifications: These are the cornerstone of management for all types of diabetes, especially T2DM and GDM.

  • Healthy Eating: Balanced diet focusing on fruits, vegetables, whole grains, lean proteins, and healthy fats. Limiting intake of sugary drinks, processed foods, and saturated/trans fats. Carbohydrate counting may be used.

  • Regular Physical Activity: Aim for at least 150 minutes of moderate-intensity aerobic activity per week, plus muscle-strengthening activities.

  • Weight Management: Losing even a small amount of weight (5-10%) can significantly improve insulin sensitivity in T2DM.

  • Smoking Cessation: Smoking significantly increases the risk of cardiovascular complications.

• Medications:

  • Insulin Therapy: Essential for all patients with T1DM. May be required for patients with T2DM when other medications are not sufficient to control blood glucose. Various types of insulin are available (rapid-acting, short-acting, intermediate-acting, long-acting) and are administered by injection or insulin pump.

  • Oral Hypoglycemic Agents (for T2DM):

    • Metformin: Often the first-line medication. Reduces glucose production by the liver and improves insulin sensitivity.

    • Sulfonylureas: Stimulate the pancreas to produce more insulin.

    • DPP-4 Inhibitors, GLP-1 Receptor Agonists, SGLT-2 Inhibitors: Newer classes of medications that work through different mechanisms to improve glucose control and may have cardiovascular benefits.

    • Other classes include Thiazolidinediones, Alpha-glucosidase Inhibitors, etc.

  • Injectable Non-Insulin Medications (for T2DM): GLP-1 Receptor Agonists are administered by injection.

• Blood Glucose Monitoring:

  • Self-Monitoring of Blood Glucose (SMBG): Patients use a glucometer to check their blood sugar levels regularly. Frequency depends on the type of diabetes, treatment regimen, and individual needs.

  • Continuous Glucose Monitoring (CGM): Devices that continuously measure glucose levels in the interstitial fluid, providing more detailed information about glucose trends.

• Education and Self-Management: Comprehensive diabetes education is crucial, covering healthy eating, physical activity, medication management, blood glucose monitoring, preventing and managing acute complications (hypoglycemia, hyperglycemia), foot care, and sick day management.

• Regular Medical Check-ups: Including monitoring HbA1c, blood pressure, lipid levels, kidney function, eye exams, and foot exams to screen for and manage long-term complications.

• Management of Comorbidities: Controlling blood pressure and cholesterol is essential to reduce cardiovascular risk.

Complications of Diabetes Mellitus

Diabetes can lead to serious acute and chronic complications affecting various organ systems.

Acute Complications:

• Diabetic Ketoacidosis (DKA): More common in T1DM. A life-threatening condition caused by severe insulin deficiency, leading to hyperglycemia, dehydration, metabolic acidosis, and ketone buildup. Symptoms include polyuria, polydipsia, nausea, vomiting, abdominal pain, Kussmaul respirations (deep, rapid breathing), fruity breath odor, and altered mental status.

• Hyperosmolar Hyperglycemic State (HHS): More common in T2DM. A life-threatening condition characterized by extremely high blood glucose levels, severe dehydration, and hyperosmolarity, without significant ketone production or acidosis. Symptoms include polyuria, polydipsia, severe dehydration, weakness, confusion, and neurological deficits.

• Hypoglycemia: Low blood glucose levels (< 70 mg/dL or < 3.9 mmol/L). Can occur as a side effect of insulin or certain oral medications. Symptoms include shakiness, sweating, confusion, dizziness, hunger, rapid heartbeat, and in severe cases, loss of consciousness or seizures.

Chronic Complications: These develop over time due to prolonged hyperglycemia and damage to blood vessels and nerves.

• Cardiovascular Disease: Diabetes significantly increases the risk of heart attack, stroke, and peripheral artery disease.

• Diabetic Nephropathy: Kidney damage, which can progress to kidney failure requiring dialysis or transplantation.

• Diabetic Retinopathy: Damage to the blood vessels in the retina of the eye, a leading cause of blindness in adults.

• Diabetic Neuropathy: Nerve damage, which can affect peripheral nerves (causing numbness, tingling, pain, or weakness in the hands and feet), autonomic nerves (affecting digestion, blood pressure, heart rate, sexual function, bladder control), or focal nerves.

• Diabetic Foot Problems: Neuropathy and poor circulation increase the risk of foot ulcers, infections, and amputations.

• Increased Susceptibility to Infections: High blood glucose impairs immune function.

• Oral Health Problems: Increased risk of gum disease and tooth loss.

• Hearing Impairment.

• Sleep Apnea.

Nursing Management

Nurses play a crucial role in the care and education of patients with diabetes.

• Assessment:

  • Assess for signs and symptoms of hyperglycemia and hypoglycemia.

  • Assess the patient’s knowledge about diabetes and its management.

  • Assess the patient’s self-care practices (diet, exercise, medication adherence, blood glucose monitoring).

  • Assess for signs of acute and chronic complications.

  • Assess the patient’s readiness to learn and their support system.

• Monitoring:

  • Monitor blood glucose levels regularly (SMBG, CGM).

  • Monitor vital signs, especially blood pressure.

  • Monitor I&O and hydration status.

  • Monitor for signs of acute complications (DKA, HHS, hypoglycemia) and initiate appropriate interventions.

  • Monitor for signs of infections.

• Medication Administration:

  • Administer insulin and oral medications as prescribed.

  • Educate patients on proper medication administration techniques (e.g., insulin injection technique, site rotation).

  • Educate patients on the purpose, dosage, timing, and potential side effects of their medications.

• Patient Education:

  • Provide comprehensive education on all aspects of diabetes self-management, including:

    • Healthy eating and meal planning.

    • Importance of physical activity.

    • Blood glucose monitoring and interpreting results.

    • Medication management.

    • Preventing and managing hypoglycemia (recognizing symptoms, carrying a source of fast-acting carbohydrate).

    • Preventing and managing hyperglycemia (sick day rules, when to call the doctor).

    • Foot care (daily inspection, proper footwear, avoiding injury).

    • Importance of regular medical check-ups and screenings.

    • Managing stress.

    • Smoking cessation.

• Promoting Healthy Lifestyle:

  • Counsel patients on healthy eating habits and physical activity.

  • Help patients set realistic goals for lifestyle changes.

• Preventing Complications:

  • Emphasize the importance of maintaining blood glucose control, blood pressure control, and cholesterol control.

  • Educate on foot care to prevent ulcers and infections.

  • Encourage regular eye exams and kidney function tests.

  • Educate on the importance of cardiovascular risk reduction.

• Emotional Support:

  • Provide emotional support to patients coping with a chronic illness.

  • Connect patients with support groups or resources.

• Collaboration:

  • Work closely with the healthcare team, including physicians, dietitians, pharmacists, and diabetes educators, to provide coordinated care.