Management of Type 2 Diabetes with HbA1c >13.9%
For a patient with type 2 diabetes and HbA1c >13.9%, initiate basal insulin immediately at 10 units daily or 0.1-0.2 units/kg body weight, continue metformin if not contraindicated, and provide diabetes self-management education with frequent glucose monitoring. 1
Immediate Treatment Approach
This level of severe hyperglycemia (HbA1c >13.9%) requires urgent insulin therapy, particularly if the patient has any symptoms of hyperglycemia such as polyuria, polydipsia, weight loss, or fatigue. 1 The American Diabetes Association explicitly recommends starting insulin therapy when blood glucose is ≥300 mg/dL or HbA1c ≥10%, especially if symptomatic, and your patient far exceeds this threshold. 1
Insulin Initiation Protocol
Start NPH insulin at 10 units once daily at bedtime, or calculate 0.1-0.2 units/kg body weight as the starting dose. 1 NPH is an acceptable intermediate-acting basal insulin option that provides relatively uniform coverage throughout the day and night, mainly suppressing hepatic glucose production between meals and during sleep. 2
NPH insulin begins working ½ hour after injection, with peak effect between 2-12 hours and duration up to 24 hours. 3 This pharmacokinetic profile makes bedtime dosing appropriate for most patients starting basal insulin.
Inject into the subcutaneous tissue of the stomach area, upper arms, buttocks, or upper legs, rotating injection sites with each dose. 3 Stomach area injection may result in faster absorption. 3
Critical Medication Decisions
Continue metformin unless contraindicated by renal impairment (eGFR <30 mL/min/1.73m²). 1, 4 The combination of metformin with insulin is superior to insulin alone, resulting in HbA1c levels approximately 10% lower (1.1 percentage points absolute reduction), requiring 29% less insulin, and preventing significant weight gain. 4
Check renal function (eGFR) before continuing metformin, as it requires dose reduction if eGFR 30-45 mL/min/1.73m² and discontinuation if eGFR <30 mL/min/1.73m². 5
Titration and Monitoring Strategy
Increase basal insulin dose by 2-4 units every 3 days based on fasting glucose values until fasting glucose reaches 80-130 mg/dL. 1 This aggressive titration is necessary given the severity of hyperglycemia.
Implement frequent home blood glucose monitoring, checking fasting glucose daily and pre-meal/bedtime glucose as needed to guide dose adjustments. 1
Recheck HbA1c in 3 months to assess response. 1, 5 With this degree of hyperglycemia, expect an HbA1c reduction of 3-4 percentage points with basal insulin plus metformin, though the patient will likely still require further intensification.
Hypoglycemia Prevention and Education
Prescribe glucagon and educate the patient and close contacts on recognition and treatment of hypoglycemia. 2 This is essential when initiating insulin therapy.
Instruct the patient to treat hypoglycemia (blood glucose <70 mg/dL) with 15-20 grams of rapid-acting carbohydrate, recheck in 15 minutes, and repeat if needed. 2
Educate on situations increasing hypoglycemia risk: fasting for procedures, during/after exercise, during sleep, and with alcohol consumption. 2, 3
When Basal Insulin Alone Is Insufficient
If fasting glucose is controlled but HbA1c remains >7% after 3 months, the patient has significant postprandial hyperglycemia requiring additional intervention. 1, 6
Add a GLP-1 receptor agonist (semaglutide, liraglutide, or dulaglutide) rather than prandial insulin as the next step. 1, 7 GLP-1 receptor agonists provide HbA1c reductions of 1.5-2.5% at baseline HbA1c >10%, cause weight loss rather than weight gain, and have lower hypoglycemia risk compared to adding mealtime insulin. 7
Only consider adding prandial insulin if GLP-1 receptor agonists are contraindicated, not tolerated, or cost-prohibitive. 1 For severe hyperglycemia with symptoms, some patients may require basal-bolus insulin from the outset. 1
Alternative to NPH: Long-Acting Insulin Analogs
While NPH is effective and less expensive, long-acting insulin analogs (glargine or detemir) are associated with modestly less overnight hypoglycemia and possibly slightly less weight gain with detemir. 2 However, NPH remains an appropriate and cost-effective option for basal insulin initiation. 2
Common Pitfalls to Avoid
Do not delay insulin initiation. At HbA1c >13.9%, oral agents alone—even in combination—will be insufficient to achieve adequate glycemic control. 1, 7
Do not mix NPH with other insulins. 3 NPH should be administered as a separate injection.
Do not target HbA1c <6.5% aggressively, as this increases hypoglycemia risk without additional cardiovascular benefits. 5 A reasonable initial target is <8%, then reassess based on patient factors. 2
Do not discontinue metformin when starting insulin unless contraindicated. 1, 4 The combination is synergistic and prevents excessive weight gain.
Do not neglect diabetes self-management education and lifestyle modifications. 2, 1 These remain foundational even when initiating insulin therapy.
Expected Outcomes
With basal insulin plus metformin, expect HbA1c reduction from >13.9% to approximately 9-10% within 3 months. 1, 4, 7 Further intensification with GLP-1 receptor agonist or prandial insulin will be necessary to reach target HbA1c <7-8%. 1