A new, reassuring study finds that men can take the diabetes drug metformin without worrying that their offspring will suffer from birth defects. Recent research raised concerns that metformin could promote birth defects in children by damaging the quality of a man's sperm. Advertisement But this study of more than 3 million pregnancies, published Wednesday in the BMJ , concluded those fears are unfounded. The new study "found no significant association between paternal metformin use during the