Diabetes Mellitus: Type 1 and Type 2 Nursing Study Guide

Diabetes mellitus is one of the most commonly tested topics in nursing exams because it affects nearly every body system and requires careful medication, monitoring, and patient-education skills. This guide compares Type 1 and Type 2 diabetes, reviews acute and chronic complications, and outlines the pharmacologic and nursing priorities you must know.

Type 1 vs Type 2 Diabetes

• Pathophysiology: Type 1 = autoimmune destruction of beta cells; Type 2 = insulin resistance.
• Onset: Type 1 is sudden and usually appears in childhood; Type 2 is gradual, typically after age 40.
• Body weight: Type 1 patients are usually lean; Type 2 patients are usually overweight or obese.
• Acute crisis: Type 1 is prone to DKA; Type 2 is prone to HHS.
• Insulin: Type 1 always requires insulin; Type 2 may not initially.
• Family history: Less common in Type 1; strongly associated in Type 2.

Risk Factors

Type 1 Diabetes

• Family history of autoimmune disease and genetic predisposition (HLA-DR3, HLA-DR4).
• Viral infections and environmental factors that trigger the autoimmune response.

Type 2 Diabetes

• Obesity (BMI ≥ 30) is the strongest risk factor.
• Family history, age over 45, sedentary lifestyle, and history of gestational diabetes.
• Hypertension, dyslipidemia, and polycystic ovary syndrome (PCOS).

What Happens in Each Type

Type 1

• The immune system attacks the pancreas and stops insulin production.
• Without insulin, glucose cannot enter cells, so the body burns fat and produces ketones.
• Insulin injections are always required and cannot be replaced with oral pills.

Type 2

• The body becomes resistant to insulin, so the pancreas works harder to compensate.
• Over time, the pancreas "tires out" and insulin production declines.
• Obesity is the main driver; weight loss can sometimes reverse the condition.

Clinical Presentation

The classic 3 Ps:

• Polyuria – frequent urination.
• Polydipsia – excessive thirst.
• Polyphagia – extreme hunger.

High glucose pulls water into the urine, causing dehydration and hunger.

• Type 1 often presents with all three Ps plus unexplained weight loss.
• Type 2 may be asymptomatic for years; some patients present only when complications develop.

Diagnosis

• Fasting glucose ≥ 126 mg/dL.
• Random glucose ≥ 200 mg/dL with symptoms.
• HbA1c ≥ 6.5%.
• Prediabetes: fasting glucose 100–125 mg/dL or HbA1c 5.7–6.4%.
• Diagnosis requires two abnormal tests on separate days, not a single high reading.

Acute Complications: DKA vs HHS

Diabetic Ketoacidosis (DKA) – Type 1

• Blood glucose > 250 mg/dL.
• Ketones present.
• Key signs: fruity breath, Kussmaul breathing, abdominal pain.

Hyperosmolar Hyperglycemic State (HHS) – Type 2

• Blood glucose > 600 mg/dL.
• Ketones absent.
• Key signs: severe dehydration, confusion, no abdominal pain.

Chronic Complications

Microvascular (Small Vessel Damage)

• Retinopathy → blindness.
• Nephropathy → kidney failure and dialysis.
• Neuropathy → numbness and pain.

Macrovascular (Large Vessel Damage)

• Coronary artery disease → heart attacks.
• Stroke → brain damage.
• Peripheral arterial disease → poor leg circulation.

Foot Problems

• Numbness plus poor healing leads to ulcers and amputation.
• Daily foot inspection and never walking barefoot are essential.
• Tight glucose control prevents microvascular but not macrovascular complications.

Treatment

Type 1 Diabetes

• Insulin is always required — never replaceable by oral pills.
• Never stop insulin in Type 1, even during illness.

Insulin Types

• Rapid-acting (Lispro, Aspart): Onset 15 min, peak 1–2 hr, duration 3–5 hr. Clear; give with meals.
• Short-acting (Regular): Onset 30–60 min, peak 2–4 hr, duration 5–8 hr. Give 30 min before meals; only insulin that can be given IV.
• Intermediate-acting (NPH): Onset 2 hr, peak 6–8 hr, duration 12–16 hr. Cloudy; must resuspend.
• Long-acting (Glargine, Detemir): Onset 2 hr, no peak, duration ~24 hr. Clear; never mix with other insulins.

Insulin Administration Rules

• When mixing Regular and NPH, draw clear before cloudy.
• Never mix long-acting insulins (glargine, detemir) with any other insulin.
• Rotate injection sites within the same area to prevent lipodystrophy.
• Absorption speed: abdomen > arm > thigh > buttock.

Type 2 Diabetes

• Begin with lifestyle changes: diet, exercise, weight loss.
• Metformin is the first-line oral medication.
• Add other agents as needed; insulin may eventually be required.

Oral and Injectable Agents

• Metformin – decreases liver glucose production. First-line; hold before contrast dye; risk of lactic acidosis.
• Sulfonylureas (Glipizide, Glyburide) – increase insulin secretion. Risk of hypoglycemia and weight gain.
• SGLT2 inhibitors (Empagliflozin) – increase glucose excretion in urine. Risk of UTIs and euglycemic DKA.
• DPP-4 inhibitors (Sitagliptin) – increase incretin levels. Weight neutral; low hypoglycemia risk.
• GLP-1 agonists (Liraglutide) – increase insulin secretion. Injectable; cause weight loss.
• Thiazolidinediones (Pioglitazone) – improve insulin sensitivity. Cause fluid retention and increase heart failure risk.

Management Targets

• Preprandial glucose: 80–130 mg/dL.
• HbA1c: < 7% for most adults.
• Blood pressure: < 130/80 mmHg.
• ACE inhibitors or ARBs preferred for BP control (kidney protection).
• Most diabetic patients over 40 need statin therapy.
• Annual eye exams, foot exams, and urine albumin testing are required.

Sick Day Rules

• Never skip insulin during illness.
• Monitor blood glucose every 2–4 hours.
• Check urine ketones if blood glucose > 250 mg/dL.
• Stay hydrated with sugar-free liquids.
• Seek medical help for vomiting, high ketones, or confusion.
• Insulin needs often increase during illness due to stress hormones.

Nursing Priorities

• Monitor blood glucose and administer medications correctly.
• Watch for DKA (fruity breath, Kussmaul breathing) and HHS (severe dehydration, confusion).
• Inspect feet daily and teach patients to never walk barefoot.
• Educate on sick day rules, hypoglycemia treatment, and medication adherence.
• Keep a fast-acting carbohydrate source available at all times.

Patient Teaching

• Keep blood sugar in target range and check feet every day.
• See an eye doctor once a year and take medications as prescribed.
• Report chest pain or leg pain with walking.
• Never skip meals or insulin; wear medical alert identification.
• Patients on insulin should carry glucagon and teach family how to use it.

Key Takeaways

• Type 1 = no insulin production, prone to DKA with ketones and Kussmaul breathing; Type 2 = insulin resistance, prone to HHS with severe dehydration and no ketones.
• Diagnose with fasting glucose ≥ 126, random glucose ≥ 200 with symptoms, or HbA1c ≥ 6.5% — confirmed on two separate occasions.
• Insulin rules: draw clear before cloudy, never mix glargine/detemir, and only Regular insulin can be given IV.
• Metformin is first-line for Type 2; hold before contrast dye to prevent lactic acidosis.
• Treat hypoglycemia (< 70 mg/dL) with 15 g fast-acting carbs; unconscious patients need IV dextrose or glucagon with side positioning.
• Prevent complications with tight glucose control, ACE/ARB therapy, statins, and annual eye, foot, and kidney screenings.