Diabetes Mellitus Overview

Aug 30, 2025

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Overview

This lecture covers the core concepts, risk factors, lab values, symptoms, complications, treatments, and key nursing care points for diabetes mellitus, focusing on exam-critical topics for NCLEX preparation.

Diabetes Mellitus Basics

  • Diabetes mellitus (DM) is a chronic condition caused by problems with insulin production or use, leading to high blood sugar.
  • Type 1 DM: Autoimmune destruction of pancreas, no insulin produced, insulin-dependent for life.
  • Type 2 DM: Insulin resistance due to poor diet/lifestyle and some genetics; the body makes insulin but cells don't respond well.
  • DM is different from diabetes insipidus, which involves excess urination, not blood sugar problems.

Blood Sugar Regulation

  • Pancreas releases insulin to lower blood sugar and glucagon to raise it by releasing stored glucose from the liver.
  • Insulin also moves potassium into cells, lowering blood levels of both.

Risk Factors & Metabolic Syndrome

  • Type 1: Mainly genetic, no lifestyle-related risk factors.
  • Type 2: Linked to obesity, poor diet, inactivity, and some genetics.
  • Metabolic syndrome (BOL): High Blood pressure (>130 systolic), Obesity (waist >35" for females, >45" for males), high Lipids (cholesterol/triglycerides), and high fasting blood glucose (>100).

Diagnosis & Key Lab Values

  • Normal glucose: 70–115 mg/dL; Fasting glucose: <100 mg/dL.
  • Hemoglobin A1C: <6.5% (shows 2–3 month blood sugar control).
  • Hypoglycemia: blood sugar <70 mg/dL; can cause brain death if untreated.

Signs, Symptoms & Causes

  • Classic DM symptoms: Polyuria (excess urination), Polydipsia (excess thirst), Polyphagia (excess hunger).
  • Causes of high blood sugar: Sepsis/infection, surgery, skipping insulin, steroids, stress.
  • Causes of low blood sugar: Exercise, alcohol, insulin peak times.

Complications

  • Chronic high blood sugar damages blood vessels, causing kidney failure (nephropathy), nerve damage (neuropathy), vision loss (retinopathy), heart disease, and strokes.
  • Foot infections and slow wound healing can lead to amputations.

Insulin Therapy & Nursing Rules

  • Type 1 always needs insulin; type 2 may need insulin if diet/exercise/oral meds fail.
  • Always give food at insulin peak times to prevent hypoglycemia.
  • Long-acting insulin: No peak, don’t mix with other insulins.
  • Only regular insulin can be given IV.
  • Draw up clear (regular) before cloudy (NPH); rotate injection sites (best: abdomen).
  • Increase insulin during stress, illness, or steroid use.
  • Always reassess blood glucose 15 minutes after treatment for hypoglycemia.

Insulin Types & Timing

  • Rapid-acting (Lispro, Aspart): Onset 15 min, peak 30–90 min. Eat within 10–15 min of injection.
  • Regular: Onset 30 min, peak 2–4 hrs. IV use allowed.
  • NPH: Onset 1–2 hrs, peak 4–12 hrs (most at risk for hypoglycemia at 5–6 hrs post-injection).
  • Long-acting (Glargine, Detemir): No peak, not food dependent.

Oral Diabetic Medications (Type 2 Only)

  • Metformin: First-line; hold 48 hrs before CT/cath lab (risk lactic acidosis); not for liver/kidney disease.
  • Sulfonylureas (glyburide, glipizide): Risk of hypoglycemia, weight gain, sunburn, heart toxicity.
  • Pioglitazone: Risk of heart failure, fluid retention.
  • Alpha-glucosidase inhibitors (acarbose): Cause GI upset; not for IBS.

Diet & Patient Education

  • Emphasize low-sugar, high-fiber complex carbs (e.g., whole grains, brown rice).
  • Avoid simple carbs (white bread, juice, candy) except for treating hypoglycemia.
  • Foot care: Inspect daily, keep clean/dry, avoid sandals/hot baths/OTC treatments, wear proper shoes/socks.
  • Therapeutic communication: Be supportive, ask open questions, encourage independence.

Key Terms & Definitions

  • Insulin resistance — Body’s cells do not respond to insulin, common in type 2 DM.
  • Hypoglycemia — Blood sugar below 70 mg/dL; causes brain dysfunction.
  • Polyuria, Polydipsia, Polyphagia — Excess urination, thirst, and hunger.
  • Acanthosis nigricans — Dark, thickened skin, sign of insulin resistance.
  • Nephropathy — Kidney damage from diabetes.
  • Neuropathy — Nerve damage from diabetes.
  • Retinopathy — Eye blood vessel damage, can lead to blindness.

Action Items / Next Steps

  • Study insulin peak times and treatment protocols.
  • Memorize metabolic syndrome criteria and key lab values.
  • Practice diabetes-related NCLEX-style questions.
  • Review foot care and dietary education points for patient teaching.

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