A more valid measurement of low-density lipoprotein cholesterol in diabetic patients.
OBJECTIVE
This study was conducted to determine if the direct low-density lipoprotein (LDL) cholesterol assay would provide a more valid measure of LDL cholesterol in diabetic patients compared with the Friedewald equation.


METHODS
Fasting plasma from 148 diabetic patients, 40 with insulin-dependent diabetes (IDDM) and 108 with non-insulin dependent diabetes (NIDDM) with triglyceride levels < 400 mg/dL, were analyzed for LDL cholesterol using the Friedewald equation, the direct LDL assay, and beta-quantification. Forty-six diabetic patients with triglyceride levels > or = 400 mg/dL were also studied to determine the validity of the direct LDL cholesterol assay with hypertriglyceridemia.


RESULTS
The friedewald equation and the direct LDL cholesterol assay correlated well with beta-quantification (r = 0.969 and r = 0.971, respectively) for LDL cholesterol determination in diabetic patients. Although the Friedewald equation in comparison with beta-quantification underestimated (8%) LDL cholesterol values in diabetic patients, the direct LDL cholesterol assay had a mean bias of < 1%. Also, the underestimation by the Friedewald equation exceeded 10% for the triglyceride subgroup of 200 to 400 mg/dL. Furthermore, the accuracy of the direct LDL cholesterol assay was superior to the Friedewald equation since LDL cholesterol levels determined by the two methods coincided within +/- 10% of beta-quantification in 85% and 68% of diabetic patients, respectively (P = 0.0005). Similar results for both the Friedewald equation and the direct LDL cholesterol assay in comparison with beta-quantification were seen when diabetic patients were subgrouped into IDDM and NIDDM. Also, the direct LDL cholesterol assay appeared to provide a reliable estimate in patients with triglycerides > or = 400 mg/dL.


CONCLUSIONS
The results of our studies indicate that the direct LDL cholesterol assay is a more reliable and accurate method than the Friedewald formula for LDL cholesterol determination in diabetic patients and is more rapid and cost effective than the reference method.
Hirany
S
S
Division of Clinical Chemistry, Parkland Memorial Hospital, USA.
Li
D
D
Jialal
I
I
D008078:Cholesterol, LDL / Q000097:blood*; D003920:Diabetes Mellitus / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D006801:Humans; D008432:Mathematical Computing; D011237:Predictive Value of Tests; D014461:Ultracentrifugation
D008078:Cholesterol, LDL