Utility of HbA1c levels for impaired glucose tolerance finding in hospitalized patients on total parental nutritional support

We evaluated the utility of hemoglobin A1c (HbA1c) levels for impaired glucose tolerance findings in hospitalized patients receiving total parental nutritional (TPN) support. From August 1 ^st to December 31 ^st 2003, there were 48 patients without diabetes history receiving TPN support at Cheng Hsin rehabilitation medical center hospital. We measured HbA1c levels on the first day and recorded other laboratory data (i.e., albumin and hemoglobin) for the next 7 days when patients were receiving TPN, and also measured blood sugar levels until the patient stopped the TPN therapy. A receiver operator characteristic (ROC) analysis was performed to assess the sensitivity and specificity of various HbA1c levels. The results revealed that HbA1c cut off of 5.6% gave the optimal sensitivity (70%) and specificity (84.2%) for patients without a diabetes history. Our data suggest that if the patient's HbA1c is greater than 5.6% on the first day of receiving TPN, that this may be a high-risk factor for hyperglycemia occurrence due to impaired glucose tolerance during the TPN support period. However, patients receiving TPN are usually in a critical condition, and there are often other contributing factors affecting blood sugar levels. Further prospective studies to examine the actual applicability and feasibility are warranted.