Dextrose Infusion in HHS Without Insulin
Yes, dextrose infusion is required in HHS when glucose falls below 14 mmol/L (250 mg/dL), even if insulin has not yet been started. This prevents hypoglycemia and allows continued fluid resuscitation while osmolality normalizes.
The Critical Timing Issue
In HHS managed initially with fluids alone (without insulin), the glucose will fall significantly from fluid replacement itself. When glucose drops to <14 mmol/L, you must start 5% or 10% dextrose infusion alongside the 0.9% saline 1. This is essential because:
- Fluid therapy alone causes substantial glucose reduction through dilution and improved renal perfusion
- The target glucose range during HHS treatment is 10-15 mmol/L in the first 24 hours 1
- Without dextrose supplementation, glucose may fall too rapidly, creating dangerous osmotic shifts
The Fluid-First Approach Context
The most recent guidelines explicitly state that insulin should be withheld until glucose stops falling with fluid administration alone (unless ketonaemia is present) 2, 1. This approach recognizes that:
- Fluid replacement is the primary intervention in HHS
- Early insulin use may be detrimental 3
- Glucose often falls from 30+ mmol/L to <14 mmol/L with fluids alone
When to Start Dextrose
Start 5% or 10% glucose infusion when blood glucose reaches <14 mmol/L 1. At this point:
- Continue 0.9% saline for volume replacement
- Add dextrose to prevent hypoglycemia
- Maintain glucose between 10-15 mmol/L for the first 24 hours
- This allows continued osmolality correction (target 3-8 mOsm/kg/h reduction) without risking hypoglycemia 1
The Target Glucose Range
Unlike DKA where glucose targets are 150-200 mg/dL (8.3-11.1 mmol/L), HHS targets are higher at 200-250 mg/dL (11.1-13.9 mmol/L) until resolution 2. However, once glucose falls below 14 mmol/L during the fluid resuscitation phase, dextrose prevents further decline while osmolality continues to normalize.
Common Pitfall
The major error is assuming that because insulin hasn't been started, dextrose isn't needed. Fluid therapy alone can drop glucose precipitously in HHS, and without dextrose supplementation at <14 mmol/L, you risk:
- Hypoglycemia
- Too-rapid osmolality changes (>8 mOsm/kg/h)
- Increased risk of cerebral edema and central pontine myelinolysis 1, 3
Bottom line: Dextrose infusion is mandatory when glucose <14 mmol/L in HHS, regardless of whether insulin has been initiated.