What is the treatment for a fasting blood sugar level greater than 300?

Treatment for Fasting Blood Sugar Greater Than 300 mg/dL

Immediate insulin therapy is mandatory when fasting blood glucose exceeds 300 mg/dL, representing severely uncontrolled diabetes requiring urgent intervention. 1, 2

Immediate Assessment and Treatment Initiation

Start basal insulin immediately at 10 units daily or 0.1-0.2 units/kg/day, along with metformin unless contraindicated (GFR <30-45 mL/min). 1, 2

Critical Pre-Treatment Assessment

Before initiating therapy, determine:

• Presence of catabolic features (weight loss, polyuria, polydipsia) or ketonuria, which indicate profound insulin deficiency and may suggest unrecognized type 1 diabetes 1, 2
• Hydration status - ensure adequate hydration before proceeding 3
• Check blood and/or urine ketones - if positive, contact physician immediately for further treatment 3

Insulin Regimen Selection

For fasting glucose >300 mg/dL with catabolic symptoms or random glucose consistently >300-350 mg/dL:

• Initiate basal-bolus insulin regimen 1, 2
• Start basal insulin at 10 units daily or 0.1-0.2 units/kg/day 2
• Add mealtime insulin at 4 units per meal or 10% of basal dose 1, 2
• Titrate basal insulin by 2 units every 3 days until fasting glucose reaches 100-130 mg/dL without hypoglycemia 2

For fasting glucose >300 mg/dL without severe symptoms:

• May start with basal insulin alone if patient feels well, is adequately hydrated, and ketones are negative 3
• Add prandial insulin if postprandial hyperglycemia persists 3

Concurrent Metformin Therapy

Metformin must be initiated simultaneously with insulin unless contraindicated. 1, 2

• Metformin is the most cost-effective agent with established cardiovascular benefits 1, 4
• The combination of insulin plus metformin effectively lowers glycemia while limiting weight gain 1
• Contraindications include GFR <30 mL/min (some guidelines suggest <45 mL/min) 2, 4

Monitoring Strategy

Implement frequent blood glucose monitoring multiple times daily until glucose levels stabilize below 200 mg/dL. 1, 2

• Test pre- and post-exercise at each session for patients on insulin or insulin secretagogues 3
• Monitor for signs of hypoglycemia or hyperglycemia 3

When to Break Fast or Delay Activity

Patients must immediately break their fast or delay exercise if: 3

• Blood glucose <60 mg/dL (3.3 mmol/L) - hypoglycemia requires immediate treatment
• Blood glucose <70 mg/dL (3.9 mmol/L) in first few hours after fasting starts (especially if on insulin or sulfonylureas)
• Blood glucose exceeds 300 mg/dL (16.7 mmol/L) - unless patient feels well, is adequately hydrated, and ketones are negative 3

Transition Strategy After Stabilization

Once glucose levels stabilize below 200 mg/dL, consider tapering insulin partially or entirely and transitioning to combination noninsulin agents. 1

• Continue metformin as foundation of long-term therapy 4
• Consider adding GLP-1 receptor agonists or SGLT2 inhibitors for additional cardiovascular benefits 4
• For patients with established cardiovascular disease, prioritize SGLT2 inhibitors or GLP-1 receptor agonists 4

Target HbA1c Goals

Aim for HbA1c between 7-8% for most patients. 1, 2, 4

• More stringent targets (6.5-7%) may be appropriate for younger patients with short disease duration, long life expectancy, and no significant cardiovascular disease 1, 2
• Less stringent targets (7.5-8.5%) are appropriate for elderly patients, those with limited life expectancy (<10 years), or advanced chronic kidney disease stages 4-5 on insulin due to increased hypoglycemia risk 2, 4

Critical Pitfalls to Avoid

Do not delay insulin initiation when fasting glucose consistently exceeds 300 mg/dL - this represents a medical urgency requiring immediate intervention, not a situation for oral monotherapy trials 1, 2

Do not overlook unrecognized type 1 diabetes - check for ketonuria in patients presenting with severe hyperglycemia and catabolic features 1

Do not allow exercise or fasting when blood glucose >300 mg/dL unless patient feels well, is adequately hydrated, and ketones are negative 3

Ensure proper insulin injection technique - advise that insulin be injected in abdomen, not muscle to be exercised 3

Caution patients that blood glucose may continue to drop for 24-48 hours after exercise when on insulin or insulin secretagogues 3

Comprehensive Risk Factor Management

Address cardiovascular risk factors concurrently with glycemic management: 1

• Blood pressure control
• Lipid management
• Smoking cessation
• These interventions remain the foundation of any type 2 diabetes treatment program 1