To elucidate the influence on charge-exchange spectroscopy of metastable deuterium donors, the corresponding cross sections for state-selective charge transfer have been calculated using the classical trajectory Monte Carlo method. The cross sections for electron capture from D(n = 2) by fully stripped low-Z ions are contrasted with those for capture from ground state D to indicate the importance of metastable donors. Using the new data, effective emission coefficients for the spectral lines of H-like light impurities used in charge-exchange spectroscopy have been calculated. These results incorporate the presence of excited n = 2 donors in the beam and apply to a wide range of neutral deuterium beam energies. For beam energies below approximately 25 keV a small fraction of D(n = 2) in the beam becomes of importance and at lower energies it even starts to dominate the charge-exchange spectroscopy observations.