Why use a dextrose (glucose) containing fluid in a patient with nausea, vomiting, and ketonuria, particularly in those with a history of diabetes?

Why Use Dextrose-Containing Fluids in Patients with Nausea, Vomiting, and Ketonuria

Dextrose-containing fluids are essential in patients with nausea, vomiting, and ketonuria because they provide the carbohydrate substrate needed to suppress ketone production and prevent or reverse starvation ketosis, while allowing continued insulin therapy to clear existing ketones. 1

Pathophysiology: Why Dextrose Stops Ketone Production

When patients cannot eat due to nausea and vomiting, the body shifts to fat metabolism for energy, producing ketones through hepatic breakdown of free fatty acids. 2 This creates a dangerous cycle:

• Without carbohydrate intake, the liver continues producing ketones even with insulin administration 1
• Ketonuria indicates active ketone production that requires both insulin AND glucose to resolve 3
• Insulin alone cannot clear ketones without adequate carbohydrate substrate—you need both 1

Evidence-Based Carbohydrate Requirements

The American Diabetes Association provides specific targets for preventing and reversing ketosis:

• Adults require 150-200 grams of carbohydrate daily (45-50g every 3-4 hours) to reduce or prevent starvation ketosis 1
• This carbohydrate requirement persists even during acute illness with hyperglycemia 1
• When oral intake is impossible due to vomiting, intravenous dextrose must replace oral carbohydrates 1

Clinical Application in Different Scenarios

For Diabetic Patients with Ketoacidosis (DKA)

When plasma glucose falls to 250 mg/dL during DKA treatment, add 5-10% dextrose to IV fluids while continuing insulin infusion. 1, 3 This critical step prevents hypoglycemia while allowing insulin to continue clearing ketones, which takes longer to resolve than hyperglycemia. 1, 3

• Ketone clearance requires 12-24 hours longer than glucose normalization 3, 4
• Stopping insulin when glucose normalizes causes recurrent ketoacidosis 3
• Dextrose infusion allows safe continuation of insulin until ketones clear completely 1, 3

For Non-Diabetic or Euglycemic Ketosis

Patients with euglycemic ketoacidosis (glucose <300 mg/dL with severe ketosis) require 10% dextrose infusions with insulin coverage. 5 This scenario occurs when:

• Vomiting prevents carbohydrate intake while insulin doses continue or increase 5
• The combination of reduced carbohydrate and continued insulin creates severe ketosis despite normal glucose 5
• Treatment requires large insulin doses covered by adequate carbohydrate via 10% dextrose 5

For Patients Unable to Take Oral Intake

When nausea and vomiting prevent oral carbohydrate intake, 5% dextrose in water at maintenance rates provides the necessary substrate. 1 Key considerations:

• This approach provides no renal osmotic load, so urine volume decreases considerably 1
• Monitor blood glucose regularly as dextrose infusion can cause hyperglycemia with subsequent osmotic diuresis 1
• Close monitoring of weight, fluid balance, and biochemistry is essential 1

Common Pitfalls to Avoid

Premature Discontinuation of Dextrose

Never stop dextrose infusion when glucose normalizes if ketones remain elevated. 3, 4 The anion gap and ketone levels must normalize before transitioning away from dextrose-containing fluids. 3

Inadequate Carbohydrate Provision

Providing fluids without dextrose in a vomiting patient with ketonuria perpetuates ketone production. 1 Even with insulin administration, the liver continues producing ketones without carbohydrate substrate. 1, 2

Misinterpreting Ketone Tests

Nitroprusside-based urine ketone tests can falsely suggest worsening ketosis during treatment as β-hydroxybutyrate converts to acetoacetate. 1, 3 This may lead clinicians to inappropriately withhold dextrose. Direct blood β-hydroxybutyrate measurement is preferred. 3

Overlooking Starvation Ketosis

Not all ketonuria represents diabetic ketoacidosis—starvation ketosis from vomiting requires dextrose but different insulin management. 1 Starvation ketosis typically shows bicarbonate >18 mEq/L, distinguishing it from DKA. 1

Practical Algorithm for Dextrose Administration

Step 1: Assess glucose level and ketone status

• If glucose >250 mg/dL with ketones: Begin standard DKA protocol with isotonic saline 1, 3
• If glucose <250 mg/dL with ketones: Consider euglycemic ketoacidosis, start 5-10% dextrose immediately 5

Step 2: Add dextrose when glucose falls during treatment

• Add 5-10% dextrose when glucose reaches 250 mg/dL in DKA 1, 3
• Continue insulin infusion at 0.05-0.1 U/kg/h despite dextrose addition 1

Step 3: Monitor resolution

• Check glucose every 1-2 hours 1
• Monitor ketones, anion gap, and bicarbonate every 2-4 hours 3
• Continue dextrose until anion gap normalizes (≤12 mEq/L) and bicarbonate >18 mEq/L 3

Step 4: Transition to oral intake

• Once nausea resolves, transition to oral carbohydrate-containing fluids 1
• Liquid carbohydrates (sugar-sweetened drinks, juices, soups) are preferred if solid food not tolerated 1