Hyperosmolar hyperglycemic state

1. History

• Key HPI: Duration of polyuria, polydipsia, weight loss; oral intake and hydration status; medication adherence; recent illness/fever/infection
• Symptom characterization: Insidious onset over days to weeks (unlike DKA which develops over hours) [5-6]
• Timing/triggers: Recent infection (most common — pneumonia, UTI, sepsis), stroke, MI, surgery, medication changes [2][5]
• Associated symptoms: Progressive weakness, fatigue, visual changes, nausea/vomiting, altered mental status ranging from lethargy to coma [5-6]
• Important negatives: Absence of Kussmaul respirations and fruity breath odor (these suggest DKA rather than pure HHS); absence of abdominal pain (more common in DKA) [3]

2. Alarm Features

• Altered mental status / coma — correlates with osmolality >330 mOsm/kg [7]
• Hemodynamic instability — hypotension, tachycardia from profound dehydration (average fluid deficit 8–12 L) [5]
• Seizures — focal or generalized, may occur with severe hyperosmolality
• Signs of precipitating illness: fever/sepsis, chest pain (ACS), focal neurologic deficits (stroke) [2]
• Mixed DKA-HHS — carries higher mortality than either condition alone [1][8]

3. Medications

Precipitating medications: [9-11]

• Glucocorticoids — most common drug class
• Atypical antipsychotics (olanzapine, clozapine, quetiapine)
• Thiazide diuretics and loop diuretics (dehydration + hyperglycemia)
• Phenytoin — impairs insulin secretion
• Beta-blockers — mask symptoms, impair insulin release
• Immune checkpoint inhibitors
• Benzodiazepines — associated with HHS precipitation in elderly [12]

4. Diet

• NPO initially — patients are often obtunded; aspiration risk is high due to gastroparesis from hypertonicity
• Hydration is paramount — average 9 L of IV fluids over 48 hours in adults [5]
• Post-recovery: Structured diabetes dietary education, carbohydrate-controlled diet
• Long-term: Adequate daily fluid intake, especially in elderly or cognitively impaired patients who may not self-hydrate

5. Review of Systems

• Neuro: Mental status changes, focal deficits, seizures, vision changes
• Infectious: Fever, cough, dysuria, skin/wound infections (most common precipitant)
• Cardiovascular: Chest pain, dyspnea (rule out ACS as trigger)
• GI: Nausea, vomiting, abdominal pain (less prominent than DKA)
• Musculoskeletal: Muscle pain/weakness (rhabdomyolysis) [15-16]
• Vascular: Limb pain, swelling (thromboembolism) [17]

6. Collateral History and Family History

• Collateral: Medication compliance, baseline functional/cognitive status, recent sick contacts, access to fluids (nursing home residents, cognitively impaired patients at highest risk)
• Family history: Type 2 diabetes, cardiovascular disease
• Social context: Living situation (isolated elderly), substance use, access to medications and healthcare [5]

7. Risk Factors

• Age >65 years — median age at presentation is 69 years [4]
• Type 2 diabetes (most common), though incidence per capita is actually higher in type 1 diabetes [4]
• Undiagnosed diabetes — 32% of HHS cases are the initial presentation of diabetes [4]
• Nursing home/institutional residence — limited access to free water
• Cognitive impairment/dementia — impaired thirst mechanism and self-care
• Renal insufficiency
• Comorbidity burden — higher Charlson Comorbidity Index independently predicts mortality [14]
• Medication nonadherence [5]
• Infection — present in ~40% of cases as the precipitant [18]

8. Differential Diagnosis

• DKA — acidosis (pH <7.3), elevated ketones, lower glucose threshold (>250 mg/dL); Kussmaul breathing present [19]
• Mixed DKA-HHS — ~27–38% of hyperglycemic crises have overlapping features; carries the highest mortality [1][8]
• Stroke — can both mimic and precipitate HHS; focal deficits may be from hyperosmolality alone
• Sepsis — may coexist; lactic acidosis may confound the picture
• Acute coronary syndrome — can trigger HHS; troponin should be checked
• Drug intoxication / toxic ingestion — check osmol gap
• Central diabetes insipidus — hypernatremia and dehydration but normal glucose

9. Past Medical History

• Prior episodes of HHS or DKA
• Type 2 diabetes — duration, HbA1c, current regimen
• Cardiovascular disease, CKD, cerebrovascular disease
• Psychiatric illness (antipsychotic use)
• Prior infections, immunocompromised state
• Surgical history (recent procedures can precipitate)

10. Physical Exam

• Vitals: Tachycardia, hypotension (orthostatic or frank), tachypnea (but NOT Kussmaul pattern in pure HHS), hypothermia or fever
• Dehydration: Dry mucous membranes, poor skin turgor, sunken eyes, delayed capillary refill
• Neuro: GCS assessment — lethargy, obtundation, coma; focal deficits may be present (hemiparesis, aphasia from hyperosmolality); seizures [5-6]
• Absent Kussmaul breathing — distinguishes from DKA
• Absent fruity/acetone breath — distinguishes from DKA [3]
• Abdominal exam: Distension (gastroparesis), tenderness (evaluate for surgical abdomen as precipitant)
• Extremities: Check for signs of DVT, peripheral vascular compromise [17]

11. Lab Studies

12. Imaging

• Chest X-ray: First-line — evaluate for pneumonia (common precipitant), pulmonary edema from aggressive fluid resuscitation
• CT head: Indicated if focal neurologic deficits, seizures, or failure to improve with treatment — rule out stroke (both precipitant and mimic) [7]
• CT abdomen/pelvis: If abdominal pathology suspected as precipitant (pancreatitis, bowel ischemia)
• Imaging is unnecessary if the clinical picture is straightforward with a clear precipitant and expected neurologic findings for the degree of hyperosmolality

13. Special Tests

• Serum osmolality calculator[20]
• Corrected sodium: Add 1.6 mEq/L to measured Na⁺ for every 100 mg/dL glucose above 100 mg/dL — corrected Na⁺ is hypernatremic in 95% of HHS cases [20]
• Anion gap: Calculate to assess for concurrent metabolic acidosis / mixed DKA-HHS
• Point-of-care glucose: Immediate bedside confirmation
• Urine/blood ketones: Rule out significant ketosis

14. ECG

• Obtain on all patients — both to evaluate for ACS as a precipitant and to assess electrolyte-related changes
• Hypokalemia findings (common during treatment): Flattened/inverted T waves, U waves, ST depression, prolonged QT, widened QRS
• Hyperkalemia findings (may be present initially): Peaked T waves, widened QRS, sine wave pattern
• Ischemic changes: ST elevation/depression, new Q waves — ACS can precipitate HHS [2]
• Arrhythmias: Atrial fibrillation (dehydration), ventricular arrhythmias (electrolyte shifts)
• Continuous telemetry recommended during treatment given rapid electrolyte shifts

15. Assessment

• HHS is an endocrine emergency with mortality 10–20% historically, though recent data show improvement to ~0.77% inpatient mortality in some series while other cohorts report 17% for pure HHS [1][3-4]
• Severity correlates with osmolality: Mental status changes typically begin at >330 mOsm/kg; coma at >340–350 mOsm/kg [7]
• Atypical presentations: Younger patients (rising incidence in obese adolescents with new-onset T2DM); mixed DKA-HHS (~27–65% of cases depending on criteria used) [8][15][20]
• Key complications: Thromboembolism (arterial and venous — far greater risk than DKA), rhabdomyolysis, AKI, cerebral edema (especially pediatric), DIC, mesenteric ischemia [7][15-17][21]
• Mortality predictors: Elevated BUN, cystatin C, D-dimer, Charlson Comorbidity Index, age, infection as trigger [14][18]

16. Treatment Plan

17. Disposition

• ICU admission is generally required for all patients with HHS — these are critically ill patients requiring continuous monitoring, IV insulin infusion, and frequent lab reassessment [6]
• Step-down/telemetry: Consider once osmolality normalizing, mental status improving, hemodynamically stable, and transitioned to subcutaneous insulin
• Specialist consultation: Endocrinology (all cases), nephrology (if rhabdomyolysis or severe AKI), vascular surgery (if arterial thrombosis), neurology (if stroke suspected)
• Discharge criteria: Osmolality <315 mOsm/kg, glucose <250 mg/dL, mental status at baseline, tolerating oral intake, stable on subcutaneous insulin regimen, precipitant treated

Critical pitfall: Transition to subcutaneous insulin must include basal insulin given 2–4 hours before stopping IV insulin to prevent rebound hyperglycemia [1][23]

18. Follow Up / Return Precautions

• Follow-up: Endocrinology within 1–2 weeks of discharge; PCP within 1 week [1]
• Discharge education: [1][9]
  • Sick day rules: Never stop insulin; increase glucose monitoring during illness; maintain hydration
  • Signs/symptoms requiring immediate return: persistent vomiting, inability to keep fluids down, confusion, glucose >400 mg/dL, fever unresponsive to treatment
  • Medication adherence counseling
  • Ensure access to glucose monitoring supplies and insulin
• Expected recovery: Mental status typically improves within 24–48 hours with osmolality correction; full metabolic normalization over 48–72 hours
• Recurrence prevention: Many patients post-HHS can be managed long-term with oral agents ± insulin once the acute precipitant resolves; structured diabetes education reduces readmission [1][11]
• Long-term mortality risk: Patients discharged after hyperglycemic crises have a 1-year age-corrected mortality rate 13 times higher than the general population [1]