Novel squaric acid compounds of the formula (I), in which R, R.sup.1, R.sup.1', R.sup.2 and X have the meanings indicated in Claim (1), are SGK inhibitors and can be used for the treatment of SGK-induced diseases and complaints, such as diabetes, obesity, metabolic syndrome (dyslipidaemia), systemic and pulmonary hypertonia, cardiovascular diseases and renal diseases, generally in fibroses and inflammatory processes of any type.