Altered D-chiro-inositol urinary clearance in women with polycystic ovary syndrome

Diabetes Care. 2006 Feb;29(2):300-5. doi: 10.2337/diacare.29.02.06.dc05-1070.

Abstract

Objective: Evidence suggests that some actions of insulin are effected by inositolphosphoglycan (IPG) mediators. We hypothesize that a deficiency in D-chiro-inositol (DCI) and/or a DCI-containing IPG (DCI-IPG) may contribute to insulin resistance in humans.

Research design and methods: To assess this possibility in polycystic ovary syndrome (PCOS), we determined insulin sensitivity (Si by frequently sampled intravenous glucose tolerance test), plasma and urinary DCI and myo-inositol (MYO) levels (by gas chromatography/mass spectrometry), and the release of insulin and DCI-IPG during the oral glucose tolerance test (area under the curve [AUC]) in 23 women with PCOS and 26 normal women.

Results: Women with PCOS were heavier than control subjects (P = 0.002 for BMI), but also had decreased Si (P < 0.001) and increased AUC(insulin) (P < 0.001) compared with normal women, even when corrected for BMI. The urinary clearance of DCI (uCl(DCI)) was increased almost sixfold in PCOS compared with normal women (P = 0.001), but not MYO clearance (P = 0.10). uCl(DCI) correlated inversely with Si when all women were analyzed together (n = 49, r = -0.50, P < 0.001) and was one of the three best independent parameters predicting Si. Finally, the ratio of AUC(DCI-IPG) to AUC(insulin) was decreased threefold in women with PCOS (P < 0.001).

Conclusions: uCl(DCI) is inversely correlated with insulin sensitivity in women and is a strong independent predictor of insulin resistance in multivariate models. PCOS, which is characterized by insulin resistance, is associated with a selective increase in uCl(DCI) and impaired DCI-IPG release in response to insulin. These findings are consistent with a defect in tissue availability or utilization of DCI in PCOS that may contribute to the insulin resistance of the syndrome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Blood Pressure
  • Body Mass Index
  • Female
  • Glucose Tolerance Test
  • Humans
  • Inositol / blood
  • Inositol / urine*
  • Insulin / metabolism*
  • Insulin Resistance / physiology*
  • Logistic Models
  • Multivariate Analysis
  • Polycystic Ovary Syndrome / metabolism*
  • Polycystic Ovary Syndrome / physiopathology
  • Testosterone / blood
  • Waist-Hip Ratio

Substances

  • Insulin
  • Testosterone
  • Inositol