Diabetes mellitus (etiologic types)

name: Diabetes Mellitus
display_name: Diabetes mellitus (etiologic types)
creation_date: "2026-07-25T00:00:00Z"
description: >-
  Diabetes mellitus is a clinically convergent group of etiologically distinct
  disorders that share the defining feature of chronic hyperglycemia arising from
  defects in insulin secretion, insulin action, or both. This grouping is a
  curated union over the mechanistically distinct diabetes Disease entries
  (autoimmune type 1, insulin-resistant type 2, and malnutrition-related /
  "type 5"), which are deliberately kept as separate entries because they differ
  in primary mechanism, genetics, body habitus, ketosis propensity, and
  treatment. They converge downstream on a shared chronic-hyperglycemia-driven
  micro- and macrovascular complication cascade.
grouping_basis:
- SHARED_PHENOTYPE
- CLINICAL_CONVENTION
grouping_rationale: >-
  Grouped on a shared defining phenotype (chronic hyperglycemia) and long-standing
  clinical convention, NOT on a shared upstream mechanism: the members reach
  hyperglycemia by fundamentally different routes. Type 1 is a T-cell-mediated
  autoimmune destruction of beta cells producing absolute insulin deficiency;
  type 2 is peripheral insulin resistance with progressive beta-cell secretory
  failure and relative insulin deficiency; malnutrition-related (type 5) diabetes
  is insulin deficiency from impaired beta-cell development/function in the
  setting of chronic undernutrition. The members are therefore kept as separate
  Disease entries rather than merged into one; this grouping sits over those
  distinct entities and records why they belong together while remaining
  mechanistically split. The shared downstream chronic-hyperglycemia complication
  cascade (AGE-RAGE / oxidative stress -> endothelial dysfunction -> micro- and
  macrovascular injury) is the convergence point common to all members.
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0005015
      label: diabetes mellitus
    mapping_predicate: skos:closeMatch
    mapping_source: MONDO
    mapping_justification: >-
      The grouping concept corresponds closely to the MONDO diabetes mellitus
      class. closeMatch (rather than exactMatch) is used deliberately: the
      retained umbrella Disease entry (kb/disorders/Diabetes_Mellitus.yaml) still
      carries MONDO:0005015 as its disease_term for its has_subtypes catalog and
      disease-level framing, so a single MONDO class is not exclusively claimed
      by the grouping. The grouping is a curated union over the standalone
      mechanistically-distinct member entries and stands on its own rationale
      rather than recapitulating the MONDO hierarchy. MONDO diabetes subtypes
      without standalone DisMech Disease entries (e.g. gestational, neonatal
      diabetes) are curation gaps; monogenic MODY is a planned additional member
      arriving in a separate follow-up PR.
    consistency:
    - reference: MONDO
      consistent: CONSISTENT
      notes: >-
        All listed members are is-a descendants of MONDO:0005015. Additional
        MONDO descendants without DisMech entries should be surfaced as
        curation gaps from this close mapping.
membership_criteria:
- description: >-
    A disorder belongs to the diabetes mellitus grouping if chronic hyperglycemia
    is a defining, near-universal feature of the disease (whatever the upstream
    route by which insulin secretion or action fails).
  criteria_semantics: NECESSARY
  logic:
    criterion_predicate: HAS_PHENOTYPE
    description: Chronic hyperglycemia is present in essentially all cases.
    phenotype_term:
      preferred_term: Hyperglycemia
      term:
        id: HP:0003074
        label: Hyperglycemia
    min_frequency: FREQUENT
members:
- member: Type I Diabetes
  member_type: DISEASE
  display_name: Type 1 diabetes mellitus
  differentiating_mechanisms:
  - description: >-
      Genetically susceptible (notably HLA class II) autoimmune, T-cell-mediated
      destruction of insulin-producing pancreatic beta cells, producing ABSOLUTE
      insulin deficiency, islet autoantibodies, lifelong exogenous-insulin
      dependence, and a propensity to diabetic ketoacidosis. Distinguished from
      type 2 by autoimmunity and absolute (rather than relative) insulin loss.
- member: Type 2 Diabetes Mellitus
  member_type: DISEASE
  display_name: Type 2 diabetes mellitus
  differentiating_mechanisms:
  - description: >-
      Peripheral insulin resistance (muscle, liver, adipose) with compensatory
      hyperinsulinemia that eventually fails as beta-cell secretory capacity
      declines, giving RELATIVE insulin deficiency; hepatic glucose overproduction
      and incretin-axis dysfunction contribute. Driven by adiposity, physical
      inactivity, and polygenic susceptibility; typically ketosis-resistant.
      Distinguished from type 1 by insulin resistance and preserved (if
      inadequate) endogenous insulin.
- member: Malnutrition-Related Diabetes Mellitus
  member_type: DISEASE
  display_name: Malnutrition-related diabetes mellitus (type 5)
  differentiating_mechanisms:
  - description: >-
      Insulin deficiency from impaired pancreatic beta-cell development and
      function in the setting of early-life and ongoing chronic undernutrition,
      rather than autoimmunity or insulin resistance. Affected individuals are
      typically lean and present with marked hyperglycemia yet relative
      resistance to ketosis, distinguishing it from type 1. Seen predominantly
      in low-resource settings.
notes: >-
  This grouping unions the mechanistically distinct diabetes Disease entries that
  currently exist as standalone files (type 1, type 2, malnutrition-related/type
  5). Monogenic MODY is planned as an additional standalone member but is being
  landed in a separate follow-up PR (it requires its own deep-research artifact
  and GeneReviews baseline per the curation SOP); it should be added here as a
  member once that entry merges. Other etiologic subtypes (gestational, neonatal,
  mitochondrial/MIDD) are still modeled as has_subtypes within the
  Diabetes_Mellitus disease entry rather than as standalone Disease files; when
  any is promoted to its own entry it should be added here as an additional
  member. See the companion migration note for the refactor separating the shared
  complication cascade from the type-specific upstream mechanisms.