Hypoglycaemia unawareness in insulin-dependent diabetes mellitus

Determination of Insulin Requirements: Excessive Insulin Dosages Common in Type 1 Diabetes Mellitus

OBJECTIVE

To report our experience of determining insulin requirements for initiating continuous subcutaneous insulin infusion (CSII) pump therapy, using an algorithm for intravenous administration of insulin, in patients with poorly controlled diabetes.

METHODS

We describe assessment of insulin requirements and analyze data from 27 consecutive admissions. All patients had type 1 diabetes mellitus and were being converted to CSII pump therapy. Twenty-four-hour intravenous insulin requirements were used to initiate CSII pump therapy, and further dose adjustments were undertaken, to optimize glycemic control. Basal, bolus, and total daily insulin requirements were calculated before, during, and 3 months after conversion to CSII therapy.

RESULTS

At entry, the mean glycohemoglobin was 11.2% (normal, 5.0 to 8.0%), and the mean daily insulin dose were 45.8 U (0.59 U/kg). Calculated daily insulin requirements using an algorithm for intravenously administered insulin were 37.3 U (0.50 U/kg). At 3 months, mean daily insulin requirements had increased to 39.2 U (0.52 U/kg), and glycohemoglobin improved to 9.4%. Most patients (78%) remained on insulin doses within 10% of the calculated requirements. All patients who were receiving more than 0.6 U/kg daily before assessment required a reduction in insulin dosage to improve glycemic control.

CONCLUSION

Many patients with type 1 diabetes are receiving excessive insulin doses. An algorithm for intravenous administration of insulin may be useful for determining requirements and appropriate insulin doses for CSII pump therapy, especially in patients with poor glycemic control.