Thiazolidine derivations of the general formula:
wherein R 1 is alkyl, cycloalkyl, phenylalkyl, phenyl, a five-or six-membered heterocyclic group including one or two hetero-atoms selected from nitrogen, oxygen and sulphur or a group of the formula
(where R 3 and R 4 are the same or different and each is lower alkyl or R 3 and R 4 are combined with each other either directly or interrupted by a hetero-atom selected from nitrogen, oxygen and sulphur to form a five- or six-membered ring); R 2 means a bond or a lower alkylene group; L 1 and L 2 are the same or different and each is lower alkyl or L' and L 2 are combined to form an alkylene group, provided that, when R' is other than alkyl, L' and L 2 may be further hydrogen,
are novel compounds and useful as, for example remedies for diabetes, hyperlipemia and so on of the mammals including human beings.