We report a male infant with transient neonatal diabetes mellitus (TNDM; MIM 601410), macroglossia, hypertelorism, umbilical hernia, inguinoscrotal hernia and onychomycosis. Diabetes mellitus was diagnosed 10 days after birth and resolved after 6.5 months of treatment. Genetic investigation indicated the presence of paternal uniparental disomy of chromosome 6 (UPD 6). The finding of paternal UPD 6 allows prediction of a transient, rather than permanent NDM, and no increased recurrence risk of TNDM in subsequent pregnancies. Therefore, finding of NDM should be a strong indicator for genetic testing.