{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,20]],"date-time":"2026-08-20T19:27:59Z","timestamp":1787254079946,"version":"build-2736575974"},"reference-count":34,"publisher":"American Diabetes Association","issue":"9","license":[{"start":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T00:00:00Z","timestamp":1784678400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.diabetesjournals.org\/journals\/pages\/license"}],"content-domain":{"domain":["diabetesjournals.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:sec>\n                    <jats:title>OBJECTIVE<\/jats:title>\n                    <jats:p>In menstruating individuals with type 1 diabetes, hormonal fluctuations across the menstrual cycle may alter insulin sensitivity and glycemia, despite advances in automated insulin delivery (AID) systems. This study aimed to characterize glycemic patterns, insulin requirements, and insulin sensitivity across menstrual cycle phases.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESEARCH DESIGN AND METHODS<\/jats:title>\n                    <jats:p>We conducted a decentralized, observational study using real-world data donated by menstruating adults reporting regular menstrual cycles and using an AID system. Participants self-enrolled and contributed anonymized continuous glucose monitoring (CGM), insulin delivery, carbohydrate intake, and menstrual cycle data. Glycemic outcomes and insulin requirements were compared across cycle phases. Cycle phase\u2013specific variation in insulin sensitivity was quantified using a hierarchical Bayesian state-space model that estimates a latent insulin sensitivity parameter from CGM time series data.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS<\/jats:title>\n                    <jats:p>Seventy-seven individuals contributed 380 menstrual cycles. Insulin requirements, carbohydrate intake, and glycemic outcomes showed systematic variation across cycle phases. Total daily insulin dose and carbohydrate intake peaked during the luteal phase, accompanied by higher mean glucose and reduced time in range. At the population level, model-derived estimates indicated greater insulin sensitivity (+2.6%, credible interval [CrI] 0.3, 5.0) in the early follicular compared with the midluteal phase (\u22122.6%, CrI \u22125.2, \u22120.1). Although 84.7% of participants showed patterns consistent with the population-level trend, substantial interindividual heterogeneity was observed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS<\/jats:title>\n                    <jats:p>Our findings confirm phase-dependent variation in insulin needs, glycemic outcomes, and insulin sensitivity across the menstrual cycle and highlight that sex-specific physiology is an important factor in glycemic regulation that is not yet addressed by current guidelines and AID systems.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.2337\/dc26-0692","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T05:01:47Z","timestamp":1784696507000},"page":"1673-1680","update-policy":"https:\/\/doi.org\/10.2337\/ada-journal-policies","source":"Crossref","is-referenced-by-count":0,"title":["Effects of Menstrual Cycle on Insulin Sensitivity in Type 1 Diabetes: An Observational Study of Individuals Using an Automated Insulin Delivery System"],"prefix":"10.2337","volume":"49","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1600-5925","authenticated-orcid":false,"given":"Stefanie","family":"Hossmann","sequence":"first","affiliation":[{"name":"Diabetes Center Berne 1 , Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-8611-4733","authenticated-orcid":false,"given":"Maya","family":"Friedman","sequence":"additional","affiliation":[{"name":"Tidepool Project 2 , Palo Alto, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-5516-2573","authenticated-orcid":false,"given":"Aritz","family":"Lizoain","sequence":"additional","affiliation":[{"name":"Diabetes Center Berne 1 , Bern, Switzerland"},{"name":"Graduate School for Cellular and Biomedical Sciences, University of Bern 3 , Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8941-4274","authenticated-orcid":false,"given":"Madleina","family":"Caduff","sequence":"additional","affiliation":[{"name":"Diabetes Center Berne 1 , Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-4872-5082","authenticated-orcid":false,"given":"Vincent","family":"Braunack-Mayer","sequence":"additional","affiliation":[{"name":"Diabetes Center Berne 1 , Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-1521-6275","authenticated-orcid":false,"given":"Laura","family":"Burlando","sequence":"additional","affiliation":[{"name":"Tidepool Project 2 , Palo Alto, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8055-944X","authenticated-orcid":false,"given":"Rayhan A.","family":"Lal","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Departments of Medicine and Pediatrics, Stanford University 4 , Stanford, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7992-9506","authenticated-orcid":false,"given":"Eda","family":"Cengiz","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Department of Pediatrics, University of California, San Francisco 5 , San Francisco, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6590-245X","authenticated-orcid":false,"given":"Katarina","family":"Braune","sequence":"additional","affiliation":[{"name":"Hasso Plattner Institute for Digital Engineering, University of Potsdam 6 , Potsdam, Germany"},{"name":"Institute of Medical Informatics, Charit\u00e9\u2013Universit\u00e4tsmedizin Berlin 7 , Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2692-8643","authenticated-orcid":false,"given":"Susanne","family":"Reger-Tan","sequence":"additional","affiliation":[{"name":"Heart and Diabetes Center, Department of Diabetes and Endocrinology, Ruhr-University 8 , Bochum, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8212-571X","authenticated-orcid":false,"given":"Antje","family":"Knopf","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern 9 , Bern, Switzerland"},{"name":"Sitem Center for Translational Medicine and Biomedical Entrepreneurship, University of Bern 10 , Bern, Switzerland"},{"name":"Department of Digital Medicine, University of Bern 11 , Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6190-7405","authenticated-orcid":false,"given":"Thomas","family":"Z\u00fcger","sequence":"additional","affiliation":[{"name":"Department of Endocrinology, Diabetes and Metabolism, Kantonsspital Olten 12 , Olten, Switzerland"},{"name":"Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism, Inselspital, Bern University Hospital, University of Bern 13 , Bern, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3084-391X","authenticated-orcid":false,"given":"Saira","family":"Khan-Gallo","sequence":"additional","affiliation":[{"name":"Tidepool Project 2 , Palo Alto, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8009-4104","authenticated-orcid":false,"given":"Martina","family":"Rothenb\u00fchler","sequence":"additional","affiliation":[{"name":"Diabetes 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