Unable to walk suddenly

Patient: Hi,My dad has type 2 diabetes mellitus . He went abroad to hajj, where he walked for 2 days in heat. He said he had very little to eat and water was also very scant. He also did not take his diabetes pills as he had nothing to eat. After 2 days, he suddenly stopped walking. he was just unable to walk. he had symptoms of vertigo on standing. After that when he was hospitalized, his sugar showed to be 500+. After treatment, he is feeling better but he is still not able to walk. Please help me with what this means and guide me. I has not returned yet from Hajj.Thank you.

Symptoms: Vertigo, unable to walk