Insulin and Diabetes Review

Insulin and Diabetes: Review

• Insulin is synthesized by the pancreas' beta cells in the Islets of Langerhans.
• Insulin is released primarily when blood sugar levels increase, typically after meals rich in carbohydrates.
• Insulin deficiency is a common consequence of diabetes.
• Consequences of insulin deficiency include:
  • Increased serum blood glucose levels.
  • Decreased cellular glucose uptake.
  • Increased glycogen breakdown.
• The body requires more insulin in situations such as:
  • Infection.
  • During periods of stress.

Insulin Types

• Rapid acting insulin:
  • Insulin lispro (Humalog) & Insulin aspart (Novolog) are examples.
  • Onset: 15-30 minutes.
  • Peak: 0.5-2.5 hours.
  • Duration: 3-6 hours.
  • Subcutaneous injections: 15 minutes before or immediately after meals.
  • Suitable for subcutaneous pump therapy for continuous glucose control.
  • Commonly used in sliding scale insulin therapy.
• Short acting insulin:
  • Regular insulin (Humulin R, Novolin R) is an example.
  • Onset: 30-60 minutes.
  • Peak: 1-5 hours.
  • Duration: 6-10 hours.
  • Subcutaneous injection: 30 minutes pre-meal for postprandial control.
  • Subcutaneous pumps can be used for continuous glucose control.
  • May be used in sliding scale insulin therapy.
  • Can be given intravenously in acute care settings.
• Intermediate acting insulin:
  • NPH insulin (Humulin N, Novolin N) is an example.
  • Onset: 1-2 hours.
  • Peak: 6-14 hours.
  • Duration: 16-24 hours.
  • Usually administered subcutaneously twice daily at the same times each day.
  • Requires agitation before use due to its cloudy appearance.
  • Can be mixed with rapid or short-acting insulins.
• Long acting insulin:
  • Insulin glargine (Lantus) and Insulin detemir (Levemir) are common examples.
  • Onset: ~ 1 hour for Lantus, 1-2 hours for Levemir.
  • Peak: None.
  • Duration: 18-24 hours.
  • Typically administered subcutaneously once daily at the same time.
  • Both are clear insulins.
• Ultra long acting insulin:
  • Insulin degludec (Tresiba) is an example.
  • Onset: 30-90 minutes.
  • Peak: None.
  • Duration: >24 hours.
  • Administered once daily at the same time.
• Combination insulins:
  • 70% NPH insulin/30% regular insulin (Humulin 70/30, Novolin 70/30) is an example.
  • Onset: 30-60 minutes for the regular component.
  • Peak: 2-12 hours for the NPH component.
  • Duration: 10-16 hours.
• Nursing implications for insulin therapy:
  • Patient education about the different types of insulin and appropriate administration is crucial.
  • Close monitoring of blood glucose levels is essential.
  • Importance of consistent meal planning and regular exercise.
  • Hypoglycemia awareness and management are important.
  • Understanding of potential side effects, including hypoglycemia.

Non-insulin Diabetic Medications:

• Insulin sensitizers:
  • Biguanides:
    • Metformin (Glucophage) is the most commonly used.
    • Mechanism of Action (MOA):
      • Reduces hepatic glucose production.
      • Decreases insulin resistance in muscle and fat cells.
      • Slightly reduces glucose absorption in the gut.
    • Side Effects:
      • Gastrointestinal upset.
      • Lactic acidosis (rare but serious).
  • Thiazolidinediones (TZDs):
    • Rosiglitazone (Avandia) is an example.
    • MOA:
      • Improves insulin sensitivity in muscle and fat cells.
      • Reduces hepatic glucose production.
    • Side Effects:
      • Most commonly: Upper respiratory tract infections, headache, sinusitis, myalgia.
      • Increased risk of heart failure, especially in patients with pre-existing heart conditions.
• Incretin Agents:
  • GLP 1 Receptor Agonists:
    • Liraglutide (Victoza) is an example.
    • MOA:
      • Activates receptors for GLP-1, promoting insulin secretion and reducing glucagon secretion.
      • Slows gastric emptying, reducing postprandial glucose spikes.
    • Side Effects:
      • Gastrointestinal upset.
      • Allergic reactions.
      • Pancreatitis.
      • Thyroid cancer (although rare).
  • DPP 4 Inhibitors:
    • Sitagliptin (Januvia) is an example.
    • MOA:
      • Inhibits dipeptidyl peptidase-4 (DPP-4), which breaks down incretin hormones like GLP-1.
      • Increases GLP-1 levels, leading to improved insulin secretion and reduced glucagon secretion.
    • Side Effects:
      • Pancreatitis.
      • Allergic reactions.
• Insulin Secretagogues:
  • Sulfonylureas:
    • Glyclazide is an example.
    • MOA:
      • Stimulate insulin release from pancreatic beta cells.
    • Side Effects:
      • Hypoglycemia.
      • Weight gain.
      • Allergic reactions.
  • Meglitinides:
    • Repaglinide is an example.
    • MOA:
      • Similar to sulfonylureas, stimulate insulin release from beta cells.
    • Side Effects:
      • Hypoglycemia.
      • Weight gain.
• Miscellaneous:
  • SGLT 2 Inhibitors:
    • Canagliflozin is an example.
    • MOA:
      • Block the reabsorption of glucose in the kidneys, promoting its excretion in urine.
    • Side Effects:
      • Urinary tract infections.
      • Genital yeast infections.
      • Dehydration.
  • Alpha-glucosidase Inhibitors:
    • Acarbose is an example.
    • MOA:
      • Slow the breakdown of complex carbohydrates in the small intestine, reducing postprandial glucose absorption.
    • Side Effects:
      • Gastrointestinal upset.
      • Flatulence.
      • Diarrhea.