GCG and type 2 diabetes mellitus: ACDF = anterior cervical discectomy and fusion; AKI = acute kidney injury; CSDF = cervical spine decompression and fusion; ED = emergency department; GLP-1 = glucagon-like peptide-1; PCF = posterior cervical fusion; PLIF = posterior lumbar interbody fusion; PLF = posterior lumbar fusion; RA = receptor agonist; T2DM = type 2 diabetes mellitus; TLIF = transforaminal lumbar interbody fusion; UTI = urinary tract infection