Changes in insulin sensitivity, secretion and glucose effectiveness during menstrual cycle

Arch Med Res. Jan-Feb 1999;30(1):19-22. doi: 10.1016/s0188-0128(98)00008-6.


Background: Several clinical conditions suggest an effect of sex steroids on glucose homeostasis in women. Studies examining this phenomenon have yielded controversial results.

Methods: To investigate the effect of the menstrual cycle on insulin sensitivity, glucose effectiveness and acute insulin response to glucose using the tolbutamide-modified intravenous glucose tolerance test (IVGTT) during the follicular (day 8 +/- 1) and luteal (day 23 +/- 1) phases of the menstrual cycle, the authors recruited 12 healthy regularly menstruating women. All had fasting glucose concentration of < 100 mg/dl [corrected] (89.7 +/- 6.2) with no family history of diabetes mellitus; their body mass indices were < 25 kg/m2 (22.41 +/- 1.44 kg/m2).

Results: The mean insulin sensitivity (Si) values decreased during the cycle. Insulin sensitivity (Si x 10(-4)/min.mU/ml) was higher in the follicular phase (5.03 +/- 0.72) and decreased in the luteal phase (2.22 +/- 0.45) (p < 0.001). Glucose effectiveness (Sg min-1) did not change as a function of the phase of the menstrual cycle. Sg estimates were 0.0229 +/- 0.00323 in the follicular phase, and 0.0225 +/- 0.00319 (p = NS) in the luteal phase, respectively. Acute insulin response (AIRg mU/ml) was 276.4 +/- 27.8 in the follicular phase. An adaptive increase (304.4 +/- 51.1) in response to the insulin resistance during the luteal phase was observed, but this increase was not statistically significant (p = NS).

Conclusions: Knowledge of the variations in insulin sensitivity that occur during the normal menstrual cycle provides a basis of comparison for studies of other clinical conditions. Also, this phenomenon should be considered if the determination of insulin resistance is the purpose of certain epidemiological studies.

MeSH terms

  • Adult
  • Blood Glucose / analysis
  • Body Mass Index
  • Estradiol / blood
  • Female
  • Follicular Phase / physiology
  • Glucose / metabolism*
  • Glucose Tolerance Test
  • Humans
  • Insulin / metabolism*
  • Insulin Resistance / physiology*
  • Insulin Secretion
  • Islets of Langerhans / metabolism*
  • Luteal Phase / physiology
  • Menstrual Cycle / physiology*
  • Progesterone / blood
  • Reference Values


  • Blood Glucose
  • Insulin
  • Progesterone
  • Estradiol
  • Glucose