Hyperglycemia

Learning objectives

Recognize signs and symptoms of hyperglycemia
Manage and prevent hyperglycemia

Definition and mechanisms

An excessive amount of glucose circulates in the plasma, typically above 180-200 mg/dL (or 10-11.1 mmol/L), or fasting blood glucose above 125 mg/dL
Symptoms of hyperglycemia develop slowly over several days or weeks
However, symptoms may not become noticeable until even higher values (250-300 mg/dL or 13.9-16.7 mmol/L)
Due to a low insulin level or if the body can not process insulin properly (insulin resistance)
Increased rates of morbidity, mortality, and length of hospital stay

Sign and symptoms

High glucose levels in the urine
Polyphagia
Polydipsia
Polyuria
Increased thirst
Blurred vision
Feeling weak or unusually tired
Fatigue
Restlessness
Weight loss or weight gain
Dry or itchy skin
Seizures
Coma

If hyperglycemia is not treated, ketoacidosis occurs:

Fruity-smelling breath
Dry mouth
Abdominal pain
Nausea and vomiting
Shortness of breath
Kussmaul hyperventilation
Confusion
Loss of consciousness

Causes

Type 1 or type 2 diabetes mellitus
Infection/ilness
Limited physical activity
Lack of insulin
Certain medications: corticosteroids, octreotide, beta blockers, epinephrine, thiazide diuretics, statins, protease inhibitors, antipsychotic medications
Excess cortisol, catecholamines, growth hormone, glucagon

Hyperglycemia may also be seen in:

Complications

Diabetic ketoacidosis
Peripheral neuropathy
Diabetic retinopathy
Nephropathy
Gastroparesis
Heart disease
Stroke

Diagnosis

Fasting glucose tests
Glucose tolerance tests
A1c test

Management

See also diabetes mellitus type 2

Preoperative management

Consider:
- Increased rates of infection
- Medical complications including: acute kidney injury, acute coronary syndromes, and acute cerebrovascular events
Administer longer-acting analogs and the increased or continuous subcutaneous insulin infusion to cover the fasting period

Perioperative glycemic control

As long as HBA1c < 8.5%, no extra precautions are warranted, except to perform regular capillary blood glucose (CBG) measurements
Administer simultaneously glucose with premixed potassium at a fixed rate and an i.v. insulin infusion titrated according to the CBG ( variable rate IV insulin infusion)
Treat a CBG > 12.0 mmol/L
Check capillary ketones to ensure that the patient had not developed DKA

Example of variable rate continuous insulin infusion:

Blood Glucose mg/dL (mmol/L)	If BG increased from previous measurement	BG decreased from prior measurement by less than 30mg/dL	BG decreased from prior measurement by greater than 30mg/dL
> 241 (13.4)	Increase rate by 3U/h	Increase rate by 3U/h	No change in rate
211-240 (11.7-13.4)	Increase rate by 2U/h	Increase rate by 2U/h	No change in rate
181-210 (10-11.7)	Increase rate by 1U/h	Increase rate by 1U/h	No change in rate
141-180 (7.8-10)	No change in rate	No change in rate	No change in rate
110-140 (6.1-7.8)	No change in rate	Decrease rate by ½ U/h	Hold insulin infusion
100-109 (5.5-6.1)	1. Hold insulin infusion 2. Re-check BG hourly 3. Restart infusion at ½ the prior infusion rate if BG > 180mg/dL (10mmol/L)
71-99 (3.9-5.5)	1. Hold insulin infusion 2. Check BG every 30 minutes until BG > 100mg/dL (5.5mmol/L) 3. Resume BG checks every hour 4. Restart infusion at ½ the prior infusion rate if BG > 180mg/dL (10mmol/L)
70 (3.9) or lower	If BG 50-70 (2.8-3.9mmol/L), 1. Give 25mL D50 2. Repeat BG checks every 30 minutes until BG > 100mg/dL (5.5mmol/L) If BG < 50mg/dL (2.8mmol/L) 1. Give 50mL D50 2. Repeat BG every 15 minutes until > 70mg/dL (3.9mmol/L) 3. When BG > 70mg/dL, BG checks every 30 minutes until > 100mg/dL (5.5mmol/L). Repeat 50mL D50 dose if BG < 50mg/dL a second time and start D10 infusion 4. After BG > 100mg/dL (5.5mmol/L), resume hourly BG check Restart infusion at ½ the prior infusion rate if BG > 180mg/dL (5.5mmol/L)
BG: Blood Glucose, mg: milligrams, dL: deciliter, mmol: millimoles, L: liter, U: Units, h: hour, D50: 50% dextrose solution, D10: 10% dextrose solution, mL: milliliters 1. If BG > 180mg/dL (10mmol/L), start insulin infusion 2. Consider bolus dose [BG – 100/40] 3. Start rate at BG/100 = U/hr 4. Check BG hourly and correct per table