Endocrine Abstracts

Background: Maturity onset diabetes of the young (MODY) has an estimated prevalence of 1–5% in the diabetic population, but misdiagnosis as type 1 or type 2 diabetes is common. It comprises a heterogeneous group of monogenic diseases characterized by primary dysfunction of β cell, young onset, autosomal dominant inheritance, without autoimmunity and without ketosis. Early diagnosis remains a challenge with important future implications, since it allows treatment optimization, prognosis definition and genetic counseling of family members.

Objective: Characterize the parameters for the diagnosis of MODY.

Patients and methods: We studied nine cases in three successive generations of a family of 12 elements, with assessment of age at diagnosis, gender distribution, clinical manifestations, initial treatment and subsequent need for insulin. We analyzed the levels of glucose, HbA₁c, C-peptide, the presence of ketosis and anti-β cell antibodies. Molecular analysis of GCK (glucokinase) and HNF-1α (hepatocyte nuclear factor 1α) genes was performed to detect MODY mutations.

Results: The age at diagnosis was 26.1±8.2 years (16–38 years), 67% females, with a disease duration of 12.7±10.6 years. Glucose levels were 200±48 mg/dl, HbA₁c 8.5±1.5%. All patients had glucosuria. Four (44.4%) patients had nephropathy with albumin excretion rate of 215±48 μg/min; 6 (66.7%) had non-proliferative retinopathy. C-peptide levels were 2.5±1.1 ng/ml. The anti-β cell antibodies were negative in all patients and none had ketosis (no ketonuria and indetectable β-hydroxybutyrate). Genetic testing revealed a mutation in exon 6 (stop mutation Ser 371 OCH) of gene HNF-1α (MODY3). Only 2 (22.2%) patients, diagnosed at 16 and 19 years, required insulin therapy, at 32 and 25 years respectively. The remaining 7 (77.8%) patients kept up with glibenclamide treatment (2.5–15 mg/day).

Conclusion: The clinical presentation of hyperglycemia without ketosis, no anti-β cell antibodies and C-peptide levels allowed to exclude type 1 diabetes. Genetic testing enabled to confirm mutations in gene HNF-1a and guide treatment according to clinical evolution.

Keywords: MODY, type 1 diabetes, type 2 diabetes, HNF1α, GCK