Steppe Lemmings are sugar intolerant which means that their diet must be low in sugar as they are prone to diabetes. This means the majority of commercial mouse/hamster mixes will be unsuitable.
In the wild their diet would consist of green vegetation, roots, grasses, sedges, plant tubers, bulbs and a small selection of seeds. They would occasionally eat insects.
Steppe Lemmings drink a high volume of water relative to their size. This can be provided in bottle or bowl, although the latter will tend to get bedding thrown in.
Since Degu are also sugar intolerant, the mixes available for them are also suitable for inclusion in a Steppe Lemmings diet.
A good base parakeet, budgie or foreign finch seed mix can be suitable. Care must be taken to check sugar levels and the mix should not contain any dried fruit.If not available in the seed mix, sprays of millet can be given.
Dried grass such as redigrass, alfalfa and a layer of hay.
Items such as broccoli, cabbage, carrot, kale, and spinach.