HOMA is Not a Good Measure of Insulin Resistance in Pregnancy

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 806-823-Gestational Diabetes
Basic/Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-816
Claire Park*1, Trinh Chung2, Nandar M Swe3 and Eli Ipp4
1Harbor-UCLA Medical Center, Torrance, CA, 2Harbor UCLA Medical Center, 3Harbor - UCLA, Alhambra, CA, 4Los Angeles Biomedical Research Institute at Harbor-UCLA Med Ctr, Torrance, CA
The hyperinsulinemic glucose clamp is the gold standard for estimating insulin sensitivity.  However, this approach is tedious and requires skilled nursing support in an inpatient setting.  Therefore, it is not a suitable tool for widespread use.   Alternative methods include homeostasis model assessment (HOMA) which uses fasting insulin and glucose values for measurement of insulin resistance, and has been used in pregnancy. We compared HOMA value with the gold standard hyperinsulinemic glucose clamp (GC) in pregnant subjects to validate use of HOMA as a measure of insulin resistance.  We studied 11 subjects during the third trimester of pregnancy.  Fasting plasma glucose (FPG) and insulin (FPI) were measured one week earlier and again prior to the GC to calculate HOMA.  A primed continuous infusion of insulin was initiated and maintained for 2 hrs.  Glucose measurements were obtained at 5-minute intervals and a variable glucose infusion (20% dextrose) used to clamp plasma glucose levels at 90 ± 5 mg/dl.  Blood samples for plasma glucose and insulin were collected at timed intervals during the clamp.  Glucose disposal rate (GDR) was measured using the average glucose infusion rate during the last 30 minutes of insulin infusion. FPG, FPI and HOMA were measured 7.5 ± 2.2 (mean ± SD) days revealed discordant changes: FPG decreased significantly from a mean 86.8 ± 8 to 82.6 ± 9.8 mg/dl (p=0.023).  In contrast, FPI demonstrated a slight increase from 12.6 ±4 to 14.1 ±5.4 uU/ml (p=0.12) and HOMA increased from 2.71 ± 0.92 to 2.93 ±1.3 (p=0.46).  Though not significant, a decrease in FPI and HOMA was expected to coincide with the decrement in FPG.  When compared with the GC, regression analysis of HOMA and GDR yielded R = 0.699.  Using FPI and GDR, the relationship was stronger, R= 0.748. In summary, this study shows that HOMA does not correlate very well with the gold standard euglycemic clamp.  FPI alone was a better correlate with insulin resistance.  This can be explained by the paradoxically discrepant changes in glucose and insulin that occurred in the third trimester, which violate the basic assumptions of the HOMA model that was developed using glucose infusions in the non-pregnant state.  These findings suggest that in pregnancy, HOMA is unlikely to be an accurate measurement of insulin resistance. Fasting insulin, though limited by its glucose dependence, may be a better choice.

Nothing to Disclose: CP, TC, NMS, EI

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