Intravenous Glucose Tolerance Tests in Predicting Diabetes Onset in APECED: A Retrospective Cohort Study

Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) require screening for endocrine manifestations, including diabetes mellitus (DM).

This work aimed to describe changes in glucose homeostasis preceding DM onset in patients with APECED.

A retrospective cohort study was conducted on 57 Finnish patients with APECED with at least 1 intravenous glucose tolerance test (IVGTT) performed between 1971 and 2001. Observations were compared between 2 groups: patients who developed DM (DM+) and those who did not (DM-). Main outcome measures included fasting plasma glucose (FPG), fasting plasma insulin (INS), fractional glucose removal rate (K_G), and first-phase insulin response (FPIR).

Sixty-five IVGTTs were performed for 13 DM+ patients (54% females) at age 6.3 to 45.4 years before type 1 DM diagnosis at a median age of 25.0 years (range, 7.2-45.4 years) and 185 for 44 DM- patients (59% females) at age 5.9 to 61.5 years. All FPG values were between 2.9 and 6.3 mmol/L. Median (interquartile range) INS was significantly higher for the DM+ group at 9.05 mIU/L (6.13-11.20) vs the DM- group 5.20 mIU/L (3.85-7.00; P = .010) at age younger than 20 years, but no statistically significant difference was found at age 20 to 40 years (4.50 mIU/L [4.00-8.00 mIU/L] vs 5.00 mIU/L [4.00-9.00 mIU/L]; P = .434). K_G and FPIR correlated negatively with age in both groups (DM+, r = -0.393; P = .019; DM-, r = -0.277; P < .001; DM+, r_s = -0.588; P < .001; DM-, r_s = -0.217; P = .042, respectively).

Glucose tolerance decreases with age in patients with APECED. IVGTT-derived markers of glucose tolerance are not predictive of DM in APECED.