function IsAdmin: Boolean;
var
  hAccessToken: THandle;
  ptgGroups: PTokenGroups;
  dwInfoBufferSize: DWORD;
  psidAdministrators: PSID;
  x: Integer;
  bSuccess: BOOL;
begin
  Result := False;
  bSuccess := OpenThreadToken(GetCurrentThread, TOKEN_QUERY, True,
    hAccessToken);
  if not bSuccess then
  begin
    if GetLastError = ERROR_NO_TOKEN then
    bSuccess := OpenProcessToken(GetCurrentProcess, TOKEN_QUERY,
                                  hAccessToken);
  end; 
  if bSuccess then 
  begin
    GetMem(ptgGroups, 1024); 
    bSuccess := GetTokenInformation(hAccessToken, TokenGroups, 
                                    ptgGroups, 1024, dwInfoBufferSize);
    CloseHandle(hAccessToken);
    if bSuccess then 
    begin
      AllocateAndInitializeSid(SECURITY_NT_AUTHORITY, 2,
        SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS,
        0, 0, 0, 0, 0, 0, psidAdministrators);
      {$R-} 
      for x := 0 to ptgGroups.GroupCount - 1 do
        if EqualSid(psidAdministrators, ptgGroups.Groups[x].Sid) then 
        begin
          Result := True; 
          Break;
        end;
      {$R }
      FreeSid(psidAdministrators); 
    end;
    FreeMem(ptgGroups); 
  end;
end;