Characterization of Turner Syndrome-associated diabetes mellitus.

Context: Diabetes mellitus (DM) risk factors in Turner Syndrome (TS) may include autoimmunity, obesity, beta-cell dysfunction, genetic predisposition and insulin resistance (IR).

Objective: Evaluate glucose tolerance and DM risk factors in adults with TS.

Design: A single centre study with two phases. To determine the prevalence of DM and to assess diabetes risk markers comparing women with TS with and without impaired glucose tolerance (IGT).

Setting: Tertiary referral center, University College Hospitals.

Patients: 106 Women with TS (age range 18-70 years) undergoing annual health surveillance.

Interventions: Participants underwent oral glucose tolerance tests (OGTT), with additional samples for autoimmunity and genetic analysis.

Main Outcome Measure: Glucose tolerance, insulin, autoimmune and single nucleotide polymorphism (SNP) profile.

Results: OGTT screening showed that those without a previous DM diagnosis, 72.7% had normal glucose tolerance, 19.5% had IGT, and 7.6% were newly diagnosed with DM. OGTT identified more cases of DM than HbAc1 sampling alone. Women with IGT or DM were older, with higher body mass index and IR. No association was found between autoimmune markers GAD, IA-2 and ZnT8, risk karyotypes or selected SNPs and DM. In DM cases, GAD positivity was associated with requirement for insulin therapy. The median age of onset of the diagnosis of DM was 36 years (range 11-56).

Conclusions: In the spectrum of DM subtypes, TS-associated DM lies between type 1 and type 2 DM with features of both. Key factors include weight and IR. Assessing C-peptide or GAD antibodies may aid future insulin requirement.