{"id":"daa24c4c-e7c4-57cc-a110-cd5966f36925","stable_key":"3279ff78-2460-5064-bfc0-3f2987af85a0:melatonin-2026-glucose-carriers","predicate":"impairs_in_risk_carriers","statement":"Melatonin worsened glucose tolerance in MTNR1B risk carriers, while the corresponding impairment was not significant in noncarriers.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"ddd56730-1142-5979-b6b7-9b7ab0616ebb","mechanism_event_label":"The recent controlled study found a genotype-dependent response.","subject":{"id":"0f0bc1f1-d18d-5652-bc1d-98f61f7ab65c","slug":"melatonin","display_name":"Melatonin","entity_type_key":"small_molecule"},"object":{"id":"b0fcea7a-0388-5f63-b7bb-38817cd5924f","slug":"glucose-tolerance","display_name":"Glucose tolerance","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"ddd56730-1142-5979-b6b7-9b7ab0616ebb","stable_key":"3279ff78-2460-5064-bfc0-3f2987af85a0:melatonin-2026-glucose-carriers-event","event_type":"observed_intervention","label":"The recent controlled study found a genotype-dependent response.","description":"Melatonin worsened glucose tolerance in MTNR1B risk carriers, while the corresponding impairment was not significant in noncarriers.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"526ce47e-7f2a-5544-892a-328fd788f4b7","slug":"mtnr1b-rs10830963-g","display_name":"Human MTNR1B rs10830963 G risk allele","entity_type_key":"gene"},"role":"genetic_context","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"0f0bc1f1-d18d-5652-bc1d-98f61f7ab65c","slug":"melatonin","display_name":"Melatonin","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"b0fcea7a-0388-5f63-b7bb-38817cd5924f","slug":"glucose-tolerance","display_name":"Glucose tolerance","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/melatonin-research/42346809.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"a8e4b84650338084b0a878a3b06138c9ef65502d7f9b119877434421b5131bc6\", \"start_char\": 0, \"end_char\": 1941, \"text_sha256\": \"a8e4b84650338084b0a878a3b06138c9ef65502d7f9b119877434421b5131bc6\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Randomized double-blind placebo-controlled crossover physiology trial","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"5 mg oral melatonin; five-day laboratory protocol","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small genotype-stratified acute study published in 2026. Stronger carrier findings are not a population-wide diabetes risk estimate or evidence about all chronic formulations.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Melatonin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"melatonin","display_name":"Melatonin","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"21 healthy European-ancestry participants: 10 risk carriers, 11 noncarriers","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The recent controlled study found a genotype-dependent response.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[melatonin-p42346809] Melatonin Impairs Glucose Tolerance, First-Phase Insulin Secretion, and Insulin Feedback Inhibition; Interaction With MTNR1B Diabetes Risk Variant. (2026). https://pubmed.ncbi.nlm.nih.gov/42346809/ DOI: 10.2337/dc26-0164","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Insulin-modified IV glucose test and beta-cell modeling","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"d12bad6d-fad5-540f-b289-d61a7fef4bea","evidence_kind":"source_excerpt","locator":"Lines 1189-1200","start_line":1189,"end_line":1200,"excerpt":"### melatonin-2026-glucose-carriers\nMelatonin worsened glucose tolerance in MTNR1B risk carriers, while the corresponding impairment was not significant in noncarriers.\nCondition category: normal\nnutrient_topic: Melatonin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The recent controlled study found a genotype-dependent response.\norganism: 21 healthy European-ancestry participants: 10 risk carriers, 11 noncarriers\ntissue_or_cell_type: Insulin-modified IV glucose test and beta-cell modeling\nexperimental_model: Randomized double-blind placebo-controlled crossover physiology trial\nlimitations: Small genotype-stratified acute study published in 2026. Stronger carrier findings are not a population-wide diabetes risk estimate or evidence about all chronic formulations.\nexposure: 5 mg oral melatonin; five-day laboratory protocol\nevidence_span: {\"source_cache\": \"artifacts/melatonin-research/42346809.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"a8e4b84650338084b0a878a3b06138c9ef65502d7f9b119877434421b5131bc6\", \"start_char\": 0, \"end_char\": 1941, \"text_sha256\": \"a8e4b84650338084b0a878a3b06138c9ef65502d7f9b119877434421b5131bc6\"}\n[melatonin-p42346809] Melatonin Impairs Glucose Tolerance, First-Phase Insulin Secretion, and Insulin Feedback Inhibition; Interaction With MTNR1B Diabetes Risk Variant. 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