a new hydrogel made of double cross-linked glycosaminoglycans, particularly cross-linked hyaluronic acid, chondroitin or chondroitin sulfate, with reversible bonds using boronic acid or boroxol derivatives leading to new benefits. double cross-linked glycosaminoglycans, one bond via two ether unions with one hydroxyl group of each of the two glycosaminoglycans and one bond via an alkoxyboronate ester anion formed between a grafted boronate hemiester to one of the glycosaminoglycans and a steel diol function. another glycosaminoglycan. the diol function may be a main chain diol function or a diol portion of a diol functional moiety grafted to another glycosaminoglycan.