FORGE CARD #03 — Diabetic Ketoacidosis (DKA)
Medicine › Endocrinology › DKA & Diabetes Emergencies
FORGE CARD #03 — Diabetic Ketoacidosis (DKA)
Medicine › Endocrinology › DKA & Diabetes Emergencies Yield: ★★★★★ | Frequency: VERY HIGH (Q2+Q4 repeat) | Syllabus: Endocrinology-DM
🔑 ONE-LINE ANSWER
DKA = hyperglycemia + ketosis + metabolic acidosis (pH <7.3, HCO3 <18). Management sequence: IV FLUIDS FIRST (1L 0.9% NS over 1h) → THEN IV insulin (0.1 U/kg/h) → Monitor and replace K+ (total body K+ depleted despite normal/high serum K+). Missed insulin causes HYPERkalemia (not hypokalemia) — this is the single most repeated NRE diabetes pattern.
🎯 EXAM ATTACK MAP
How the NRE tests this:
- Pattern 1: Young T1DM + stopped insulin + vomiting + Kussmaul breathing + pH 7.29 + HCO3 12 → “Initial management?” → IV fluids FIRST (not insulin, not bicarb, not K+)
- Pattern 2: Diabetic on insulin + missed doses + palpitations + breathlessness → check ECG → peaked T waves → HYPERkalemia → IV calcium gluconate if ECG changes
- Pattern 3: DKA vs HHS discrimination — glucose level, pH, ketones, osmolality
- Pattern 4: T2DM on max metformin + HbA1c 10.2% + eGFR 42 → “Avoid which drug?” → Sulfonylurea (hypoglycemia risk in CKD)
- Pattern 5: DM + microalbuminuria → “First-line drug?” → ACE inhibitor (renoprotective independent of BP)
Favorite disguise: The “missed insulin → hyperkalemia” question disguised as “patient presents with palpitations and breathlessness after missing insulin.” Students who automatically think “DKA = hypokalemia” get trapped. The key: missed insulin → K+ stays extracellular → HYPERkalemia → cardiac symptoms.
Classic distractor: “Start insulin immediately” for DKA. Insulin without fluid resuscitation risks vascular collapse. Fluids first, always.
What discrimination rewards: The management SEQUENCE (fluids → insulin → K+) and the paradoxical electrolyte effect of insulin deficiency (hyperkalemia, not hypokalemia).
📋 CORE CONCEPT — MUST KNOW
DKA vs HHS Discrimination
| Parameter | DKA | HHS |
|---|---|---|
| Patient | T1DM (younger) | T2DM (older) |
| Onset | Rapid (<24h) | Gradual (days) |
| Blood glucose | 250-500 mg/dL | > 600 mg/dL |
| pH | < 7.3 (metabolic acidosis) | > 7.3 (no acidosis) |
| Serum HCO3 | < 18 mEq/L | Normal |
| Serum ketones | Positive (strong) | Negative/trace |
| Serum osmolality | Variable | > 320 mOsm/kg |
| Mental status | Alert to obtunded | Stupor/coma |
| Management | Fluids → insulin → K+ | Fluids (larger volume) → low-dose insulin |
DKA Management Algorithm
| Step | Action | Details |
|---|---|---|
| STEP 1 | IV Fluids — 0.9% Normal Saline | 1 L over 1h, then 250-500 mL/h. Fluid resuscitation BEFORE insulin. Prevents vascular collapse. |
| STEP 2 | IV Insulin | Regular insulin 0.1 U/kg bolus + 0.1 U/kg/h infusion. Do NOT start without fluids first. |
| STEP 3 | Monitor K+ closely | Total body K+ depleted despite normal/high serum K+. Replace K+ when serum <5.3. |
| Adjunct | Correct glucose | Target fall 50-70 mg/dL/h. Switch to dextrose-containing fluids when glucose <250 (to avoid hypoglycemia while continuing insulin for ketosis). |
| Adjunct | Correct acidosis | pH >7.3 = resolving. Bicarbonate only if pH < 6.9 (controversial, rarely needed). |
Missed Insulin → HYPERkalemia (Most Repeated NRE Pattern)
| Concept | Explanation |
|---|---|
| Mechanism | Insulin drives K+ into cells. Without insulin, K+ stays extracellular → serum K+ rises. |
| ECG changes | Peaked T waves → widened QRS → sine wave → VF |
| Management | IV calcium gluconate if ECG changes (membrane stabilization) → shift K+ → remove K+ |
| Trap | Students think “DKA = hypokalemia” — but MISSED insulin causes HYPERkalemia. |
Diabetic Nephropathy Progression
| Stage | Finding | Action |
|---|---|---|
| Stage 1 | Hyperfiltration, kidney enlargement | — |
| Stage 2 | Normal albumin, GBM thickening | — |
| Stage 3 | Microalbuminuria (ACR 30-300 mg/g) | ACEi/ARB — renoprotective |
| Stage 4 | Overt proteinuria, ↓ GFR | ACEi + BP control + glycemic control |
| Stage 5 | ESRD | Dialysis/transplant |
T2DM Pharmacotherapy (Stepwise)
| Step | Therapy | Key Points |
|---|---|---|
| First-line | Metformin | Obese, weight-neutral, cardioprotective. Contraindicated if eGFR <30. |
| Second-line | Add SU, DPP-4i, SGLT-2i, GLP-1 RA, or insulin | Avoid sulfonylureas in CKD (↑ hypoglycemia risk). |
| SGLT-2 inhibitors | Empagliflozin, dapagliflozin | Cardiorenal benefit |
| GLP-1 agonists | Liraglutide, semaglutide | Weight loss + CV benefit |
Diabetic Foot — Wagner Grading
| Grade | Description | Management |
|---|---|---|
| 0 | Intact skin | Offloading, education |
| 1 | Superficial ulcer | Debridement + offloading |
| 2 | Deep to tendon/capsule | Debridement + antibiotics + offloading |
| 3 | Osteomyelitis | Debridement + prolonged antibiotics ± amputation |
| 4 | Forefoot gangrene | Amputation |
| 5 | Whole foot gangrene | Amputation |
Neuropathic vs Ischaemic Foot:
- Neuropathic: WARM, bounding pulses, claw toes, PAINLESS ulcer (AV shunting)
- Ischaemic: COLD, absent pulses, painful ulcer
⚠️ TRAP FIELD — ERROR SHIELD
❌ Trap 1: DKA → insulin first
✅ Reality: Fluid resuscitation is ALWAYS first in DKA. Insulin without rehydration risks vascular collapse (insulin drives glucose AND water into cells → intravascular volume drops). Fluids first, then insulin, then K+. This sequence is non-negotiable.
❌ Trap 2: Missed insulin → hypokalemia
✅ Reality: Insulin drives K+ into cells. MISSED insulin means K+ stays extracellular → HYPERkalemia. This is the single most repeated NRE diabetes pattern. No insulin = K+ outside cells = HIGH serum K+. Think “trapped outside.”
❌ Trap 3: Somogyi → increase insulin dose
✅ Reality: Somogyi = rebound hyperglycemia from nocturnal hypoglycemia. Need to DECREASE dose, not increase. Higher AM sugars after increasing insulin = Somogyi = decrease dose.
❌ Trap 4: Glycemic control alone for diabetic nephropathy
✅ Reality: ACEi/ARB has independent renoprotective effect beyond glycemic and BP control. The answer is ACEi + BP + glucose. Even normotensive diabetics with microalbuminuria need ACEi.
❌ Trap 5: Cold neuropathic foot
✅ Reality: Neuropathic foot is WARM with bounding pulses (arteriovenous shunting). Cold foot = ischaemic, not neuropathic. Bounding pulses = neuropathic. Absent pulses = ischaemic.
❌ Trap 6: T2DM first-line = sulfonylurea
✅ Reality: Metformin is ALWAYS first-line in obese T2DM unless contraindicated (eGFR <30). Lifestyle is adjunct, not monotherapy once diagnostic thresholds are met.
🧠 MEMORY ANCHOR
“FIK” for DKA Management Sequence:
- Fluids FIRST (1L NS over 1h)
- Insulin SECOND (0.1 U/kg/h)
- K+ monitor THIRD (replace when <5.3)
“HIGH K+” for Missed Insulin:
- Hyperkalemia from missed insulin
- Insulin drives K+ IN — without it, K+ stays OUT
- Goes HIGH in serum
- Harmful ECG changes → calcium first
“Somogyi = SORRY (decrease dose)”:
- Rebound hyperglycemia from nocturnal hypoglycemia
- The dose was too high → SORRY → decrease
“ABCD” for Diabetic Foot Discrimination:
- Arterial (ischaemic) = cold, Absent pulses, Aching painful
- Bounding (neuropathic) = warm, Bounding pulses, Barely painful
🏥 CLINICAL REASONING TRIGGER
“When you see a young T1DM who stopped insulin, now vomiting with Kussmaul breathing and pH <7.3, think DKA. The discriminator is the triad: hyperglycemia + ketosis + acidosis. Management: fluids FIRST, then insulin.”
“When you see a diabetic on insulin who missed doses, now with palpitations and breathlessness, check ECG. Peaked T waves = hyperkalemia from insulin deficiency. The discriminator: insulin drives K+ into cells — without it, K+ stays extracellular = HYPERkalemia.”
“When you see an older T2DM with glucose >600 but NO ketosis and NO acidosis, think HHS. The discriminator: profound hyperglycemia + high osmolality + minimal ketones. Management: large volume fluids first.”
🔗 CROSS-LINKS
→ Hyperkalemia Management — Missed insulin → hyperkalemia → calcium gluconate if ECG changes (see Forge Card #02) → Metformin Pharmacology — First-line T2DM; contraindicated eGFR <30; lactic acidosis risk → CKD Drug Dosing — Metformin, sulfonylureas, NSAIDs in renal impairment → Acid-Base Disorders — Anion gap metabolic acidosis in DKA; MUDPILES → Diabetic Nephropathy — Microalbuminuria → ACEi; progression to ESRD → Sick-Day Rules — NEVER stop insulin during illness; increase dose
⚡ RAPID FIRE
Q1. A 14-year-old T1DM stopped insulin 2 days ago. Now vomiting, unconscious with Kussmaul breathing. ABG: pH 7.29, PaCO2 33, HCO3 12. What is the most appropriate initial management?
- A) IV insulin bolus
- B) IV sodium bicarbonate
- C) IV normal saline
- D) IV potassium chloride
- E) Subcutaneous insulin
→ Answer: C | Why: DKA management: IV fluids FIRST (1L 0.9% NS over 1h), THEN insulin. Insulin without fluids risks vascular collapse. Bicarbonate (B) is only for pH <6.9. Potassium (D) is monitored and replaced later.
Q2. A 60-year-old diabetic on insulin missed several doses and presents with palpitations and breathlessness. ECG shows tall peaked T waves. Serum K+ is 6.8. What is the most appropriate immediate management?
- A) IV insulin + dextrose
- B) IV calcium gluconate
- C) Emergency hemodialysis
- D) Oral Kayexalate
- E) IV furosemide
→ Answer: B | Why: Missed insulin → hyperkalemia (K+ stays extracellular without insulin). ECG changes (peaked T waves) = membrane instability → IV calcium gluconate FIRST to stabilize the heart. This is the most repeated NRE diabetes pattern.
Q3. A 50-year-old obese female presents with polyuria and polydipsia. RBG 170 mg/dL, HbA1c 8.5%. What is the most appropriate first-line pharmacotherapy?
- A) Sulfonylurea (glibenclamide)
- B) Insulin
- C) Metformin
- D) Lifestyle modification alone
- E) SGLT-2 inhibitor
→ Answer: C | Why: Metformin is ALWAYS first-line in obese T2DM unless contraindicated. Lifestyle modification (D) is adjunct, not monotherapy once diagnostic thresholds are met (HbA1c ≥6.5%).
Q4. A 55-year-old T2DM on max metformin has HbA1c 10.2% and eGFR 42. Which drug should be AVOIDED?
- A) DPP-4 inhibitor
- B) SGLT-2 inhibitor
- C) Sulfonylurea
- D) GLP-1 agonist
- E) Basal insulin
→ Answer: C | Why: Sulfonylureas accumulate in CKD → severe hypoglycemia risk. Metformin is safe at eGFR 42 (reduce dose if 30-45, stop if <30). SGLT-2 inhibitors and GLP-1 agonists are preferred in CKD.
✓ CONFIDENCE CHECK
“Can I explain the DKA management sequence, the missed-insulin hyperkalemia pattern, and the DKA vs HHS discrimination to a peer in 60 seconds?”
Rate: ☆☆☆☆☆
If you hesitated on any zone, revisit that section before moving on.
Source evidence: NRE Dec 2025 recalled paper, NRE May 2026 Intelligence Report (177 MCQs), NRE50 System (Q2+Q4 repeat), MedCORE Day 39 Diabetes DKA HHS, MedCORE Premium DKA_HHS, QBank Q3/Q11/Q30/Q34/Q38/Q39/Q52/Q73/Q75/Q98/Q109/Q120/Q125/Q136/Q137/Q189.