Heterogeneity in young adult onset diabetes: aetiology alters clinical characteristics.

Aims: To describe the characteristics of hepatocyte nuclear factor (HNF) 1 alpha mutation carriers diagnosed with diabetes after 25 years and compare them with young-onset Type 2 diabetic patients (YT2D) diagnosed at the same age.

Subjects And Methods: We studied 44 (21 male, 23 female) patients with HNF-1 alpha mutations diagnosed with diabetes at ages 25-45 years and 44 YT2D subjects matched for sex and age of diagnosis.

Results: Median age of onset of diabetes was 35 years in both groups. The HNF-1 alpha group demonstrated: lower body mass index (25.1 vs. 30.7 kg/m2; P < 0.001) and lower fasting triglycerides (1.37 vs. 2.96 mmol/l; P = 0.001) with similar fasting cholesterol level. They had lower glycated haemoglobin A1c (7.3 vs. 8.5%; P = 0.015) despite greater duration of diabetes (24 vs. 16 years; P = 0.02) and less frequent treatment with insulin (21% vs. 55%; P = 0.002). They were less likely to be treated for hypertension (13.3% vs. 56.3%; P = 0.009). Importantly, no difference was observed in reported parental history of diabetes between the two groups (65.9% vs. 63.6%; P = 0.92). Logistic regression showed that triglyceride levels and presence of anti-hypertensive treatment were the most important independent variables.

Conclusions: Patients with HNF-1 alpha mutations may present with diabetes as young adults between the ages of 25-45 years. In this age range a wide differential diagnosis of diabetes is observed. Conventional criteria of age of onset and family history will not differentiate HNF-1 alpha mutation carriers from YT2D subjects in this age range, but features of the metabolic syndrome, in particular fasting triglycerides and hypertension, are helpful. In patients diagnosed before 45 years without features of insulin resistance the diagnosis of HNF-1 alpha should be considered.