title: Fluctuations of Hyperglycemia and Insulin Sensitivity Are Linked to Menstrual Cycle Phases in Women With T1D.
abstract: BACKGROUND
  Factors influencing glycemic variability in type 1 diabetes (T1D) may play a significant role in the refinement of closed loop insulin administration. Phase of menstrual cycle is one such factor that has been inadequately investigated. We propose that unique individual patterns can be constructed and used as parameters of closed loop systems.
  
  
  METHODS
  Women with T1D on continuous subcutaneous insulin infusion and continuous glucose monitoring were studied for 3 consecutive menstrual cycles. Ovulation prediction kits and labs were used to confirm phase of menstrual cycle. Glycemic risks were assessed using the low- and high blood glucose indices (LBGI and HBGI). Insulin sensitivity (SI) was estimated using a Kalman filtering method from meal and insulin data. Overall change significance for glycemic risks was assessed by repeated measures ANOVA, with specific phases emphasized using contrasts.
  
  
  RESULTS
  Ovulation was confirmed in 33/36 cycles studied in 12 subjects (age = 33.1 ± 7.0 years, BMI = 25.7 ± 2.9 kg/m(2), A1c = 6.8 ± 0.7%). Risk for hyperglycemia changed significantly during the cycle (P = .023), with HBGI increasing until early luteal phase and returning to initial levels thereafter. LBGI was steady in the follicular phase, decreasing thereafter but not significantly. SI was depressed during the luteal phase when compared to the early follicular phase (P ≤ .05). Total daily insulin, carbohydrates, or calories did not show any significant fluctuations.
  
  
  CONCLUSIONS
  Women with T1D have glycemic variability changes that are specific to the individual and are linked to phase of cycle. An increased risk of hyperglycemia was observed during periovulation and early luteal phases compared to the early follicular phase; these changes appear to be associated with decreased insulin sensitivity during the luteal phase.
authors.affiliation: Center for Diabetes Technology, University of Virginia, Charlottesville, VA, USA Division of Endocrinology, University of Virginia, Charlottesville, VA, USA sab2f@virginia.edu.
authors.forename: Sue A
authors.initials: SA
authors.lastname: Brown
authors.affiliation: Center for Diabetes Technology, University of Virginia, Charlottesville, VA, USA.
authors.forename: Boyi
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Division of Endocrinology, University of Virginia, Charlottesville, VA, USA.
authors.forename: Molly
authors.initials: M
authors.lastname: McElwee-Malloy
authors.affiliation: Center for Diabetes Technology, University of Virginia, Charlottesville, VA, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Wakeman
authors.affiliation: Center for Diabetes Technology, University of Virginia, Charlottesville, VA, USA.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Breton
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D015190:Blood Glucose Self-Monitoring; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D004867:Equipment Design; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D055104:Infusions, Subcutaneous; D007328:Insulin / Q000008:administration & dosage* / Q000009:adverse effects; D007332:Insulin Infusion Systems; D007333:Insulin Resistance; D008597:Menstrual Cycle / Q000097:blood*; D008954:Models, Biological; D019397:Pancreas, Artificial; D010865:Pilot Projects; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin
keywords: artificial pancreas; closed loop control; continuous glucose monitoring; insulin pump therapy; menstrual cycle; type 1 diabetes