Endocrine Abstracts

Objectives: We have recently demonstrated a wide variation in insulin resistance (IR) occurs in polycystic ovarian syndrome and type 2 diabetes. Changes in insulin metabolism and increased insulin resistance (IR) after the menopause have previously been reported. It is unknown if the biological variation of IR is affected by the menopause and is evaluated here.
Methods: The biological variation of IR was assessed by measuring IR at four day intervals on 10 consecutive occasions in 11 healthy women (median age 30yrs, range 19-33) with normal menstrual periods and in 11 healthy, weight matched, postmenopausal women (median age 56, range 48-70). Insulin resistance was derived using the Homeostasis Model Assessment method (HOMA-IR) from fasting measures of serum insulin and plasma glucose. The study was approved by the Local Research Ethics committee.
Results: The distribution of HOMA-IR was Gaussian in both groups. The HOMA-IR in the postmenopausal group was greater than the premenopausal group (mean plus/minus SD, 2.11 plus/minus 0.79 vs. 1.67 plus/minus 0.63 units, p=.0001). Having accounted for analytical variation, the mean intra-individual variation was found to be similar in both post and premenopausal women (0.40 vs 0.48, p=0.188).
Conclusion: In accord with previous reports, we found a significant increase in insulin resistance after the menopause. Despite this change, the intraindividual variation in HOMA-IR was low in both pre and postmenopausal women suggesting it is unaffected by menopausal status.