Guide — Med-Surg
Diabetes Management Basics
Diabetes mellitus is a group of metabolic disorders characterized by chronic hyperglycemia from defects in insulin secretion, insulin action, or both. With over 37 million Americans living with diabetes, nurses encounter it in virtually every clinical setting. This guide covers the fundamentals of both types, glucose monitoring, acute complications, and nursing priorities.
11 min read · Med-Surg
Educational use only. Diabetes management requires individualized provider orders including insulin regimens, glucose targets, and diet prescriptions. Always follow institutional protocols and provider orders for glucose management. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Overview
Insulin, secreted by pancreatic beta cells, is essential for glucose uptake into cells. Without adequate insulin action, glucose accumulates in the bloodstream (hyperglycemia) while cells are starved of their primary fuel source. Over time, chronic hyperglycemia damages blood vessels and nerves, causing the microvascular and macrovascular complications that define the long-term burden of diabetes.
Key diagnostic thresholds (ADA):
- Fasting plasma glucose ≥ 126 mg/dL on two occasions
- Random plasma glucose ≥ 200 mg/dL with symptoms
- 2-hour glucose ≥ 200 mg/dL during OGTT
- HbA1c ≥ 6.5% on two occasions
Type 1 vs Type 2 Diabetes
| Feature | Type 1 | Type 2 |
|---|---|---|
| Mechanism | Autoimmune destruction of beta cells → absolute insulin deficiency | Insulin resistance + progressive relative insulin deficiency |
| Onset | Typically childhood/adolescence (but any age) | Typically adult onset; increasingly in younger patients |
| Body habitus | Usually normal or thin; weight loss at diagnosis | Often overweight or obese; central adiposity |
| Insulin required? | Always — without insulin, DKA occurs within hours to days | Not initially; may require insulin as disease progresses |
| Acute crisis risk | DKA — ketones produced due to absolute insulin deficiency | HHS (hyperosmolar hyperglycemic state) — extreme hyperglycemia without significant ketosis |
| C-peptide | Low/absent (no endogenous insulin production) | Normal or elevated (initially) |
Blood Glucose Monitoring
Consistent blood glucose monitoring is the foundation of diabetes self-management and inpatient glucose control. Point-of-care fingerstick glucose (POCT) is standard for bedside monitoring.
Inpatient glucose targets (ADA):
- ICU patients: 140–180 mg/dL (avoid < 140 mg/dL target — increased hypoglycemia risk)
- Non-critically ill: pre-meal < 140 mg/dL, random < 180 mg/dL
- Hypoglycemia treatment threshold: < 70 mg/dL (critical hypoglycemia: < 54 mg/dL)
- HbA1c: Reflects average glucose over 2–3 months. Goal: < 7% for most adults. Does not reflect day-to-day variability.
- Continuous glucose monitoring (CGM): Increasing use in hospital; provides real-time trends. Values may differ from fingerstick — verify with POCT if clinical concern.
- Frequency: Most hospitalized diabetic patients require glucose checks before each meal and at bedtime (AC/HS). Insulin infusion protocols may require hourly monitoring.
Hypoglycemia
Signs and symptoms:
- Adrenergic (early): Diaphoresis, tremulousness, tachycardia, pallor, anxiety, hunger — from sympathetic activation
- Neuroglycopenic (moderate-severe): Headache, confusion, blurred vision, difficulty concentrating, slurred speech
- Severe: Seizures, loss of consciousness, coma — brain cannot function without glucose
- Hypoglycemia unawareness: Long-term diabetics may lose adrenergic symptoms — first sign may be confusion or loss of consciousness
Treatment — Rule of 15:
- Give 15 g fast-acting carbohydrate (4 oz juice, glucose tablets, glucose gel)
- Recheck glucose in 15 minutes
- If still < 70 mg/dL, repeat 15 g
- Once glucose ≥ 70 mg/dL, provide a snack or meal if next meal is more than 1 hour away
- If patient is unconscious: IV dextrose (D50W) or IM/SC glucagon; do not give oral glucose to an unconscious patient
Hyperglycemia
Mild to moderate hyperglycemia may be asymptomatic. Significant or acute hyperglycemia produces characteristic symptoms:
- Classic triad: Polyuria, polydipsia, polyphagia (3 Ps)
- Fatigue, weakness, blurred vision, headache
- Weight loss: Particularly in Type 1 (catabolism from insulin deficiency)
- Recurrent infections: High glucose impairs immune function (UTI, skin infections)
Acute hyperglycemic crises:
- DKA (Type 1 primarily): Glucose > 250 mg/dL, ketones, metabolic acidosis, pH < 7.30, HCO₃ < 18. Kussmaul breathing, fruity breath, altered mental status.
- HHS (Type 2 primarily): Glucose often > 600 mg/dL, hyperosmolarity, minimal ketones, profound dehydration, severe mental status changes.
Insulin Basics
Insulin is the primary treatment for Type 1 diabetes and an important tool in Type 2 management. Understanding onset, peak, and duration is critical for anticipating hypoglycemia risk and timing assessments.
- Rapid-acting (lispro, aspart, glulisine): Onset 15 min, peak 1–2 hours, duration 3–5 hours. Given immediately before meals — assess that patient is able to eat before administering.
- Short-acting (regular): Onset 30–60 min, peak 2–4 hours, duration 6–8 hours. Given 30 minutes before meals; also used IV for DKA infusions.
- Intermediate-acting (NPH): Onset 2–4 hours, peak 4–10 hours, duration 12–18 hours. Given twice daily; hypoglycemia risk during peak (often mid-afternoon and nighttime).
- Long-acting (glargine, detemir, degludec): Onset 1–2 hours, minimal peak, duration 20–24+ hours. Provides basal coverage. Do not mix with other insulins (glargine/degludec).
Insulin is a high-alert medication. Verify dose with a second nurse per institutional policy before administration.
Nursing Priorities
Monitoring
- Blood glucose checks per protocol (AC/HS minimum; hourly for insulin infusions)
- Know and document glucose trends — identify patterns of hypo or hyperglycemia
- Monitor HbA1c at admission (reflects pre-hospitalization control)
- Assess for signs of hypoglycemia and hyperglycemia at every assessment
Safe Insulin Administration
- Insulin is a high-alert medication — two-nurse verification per protocol
- Never administer rapid-acting insulin if patient cannot eat or has nausea/vomiting
- Rotate injection sites to prevent lipohypertrophy (impairs absorption)
- Warm insulin to room temperature before administration if refrigerated
- Glargine/degludec: do not mix; administer at same time each day
Prevention of Complications
- Foot care: daily assessment for wounds, decreased sensation, and circulation; patient education on footwear
- Skin integrity: glucose impairs healing — assess IV sites, incisions, and pressure areas frequently
- Renal: monitor BUN/creatinine and urine output; coordinate contrast/nephrotoxic medication timing
- Infection prevention: handwashing, IV site care, glucose control — hyperglycemia impairs immune response
Patient Education
- Blood glucose monitoring: When to check, target ranges, what to do for out-of-range values
- Insulin technique: Proper injection technique, site rotation, storage of insulin, and disposal of sharps
- Hypoglycemia management: Always carry fast-acting carbohydrate; wear medical ID; Rule of 15; glucagon kit for severe episodes
- Sick day rules: Continue insulin even when not eating; check glucose more frequently; maintain hydration; notify provider if glucose > 300 or ketones are present
- Foot care: Daily inspection, no bare feet, proper footwear, nail care guidance, when to call provider
- Diet: Carbohydrate consistency; avoid concentrated sweets; consult with dietitian for individualized meal planning
NCLEX Pearls
- Type 1 = absolute insulin deficiency; Type 2 = insulin resistance + relative deficiency
- DKA = Type 1, ketones, acidosis. HHS = Type 2, extreme glucose, no significant ketones
- Hypoglycemia (< 70 mg/dL): treat first, document second — brain damage occurs rapidly
- Never give rapid-acting insulin if patient is NPO, nauseated, or cannot eat
- Insulin is high-alert — two-nurse check per protocol
- Priority for unconscious hypoglycemia: IV dextrose (D50W) — not oral glucose
- Glargine (Lantus) = clear, no peak — never mix with other insulins
- Kussmaul respirations (rapid, deep) = body compensating for metabolic acidosis in DKA
- Fruity breath = ketones (acetone) = DKA
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with Academy of Medical-Surgical Nurses (AMSN) · Current medical-surgical nursing standards. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →