How to Compare two time values (from Datetime) without Date in C#

I have put a timer on my ASPX page, Where on tick it updates the "currenttime" on a asp:label called Label1, however when the page loads I store a DateTime value called "endtime", now what i want to do is when "currenttime" equals "endtime" fire Response.Redirect(...), my code is like below,

ASPX

 <asp:ScriptManager ID="ScriptManager1" runat="server">
 </asp:ScriptManager>
 <asp:Timer ID="Timer1" runat="server" ontick="Timer1_Tick" Interval="1000">
 </asp:Timer>
 <asp:UpdatePanel ID="UpdatePanel1" runat="server">
       <ContentTemplate>
           <asp:Label CssClass="captions2" ID="Label1" runat="server" Text="Exam Timer"></asp:Label>
       </ContentTemplate>
           <Triggers>

               <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />

           </Triggers>
 </asp:UpdatePanel>

Code Behind

protected void Timer1_Tick(object sender, EventArgs e)
    {
        if(...comparison goes here....){

        Response.Redirect("Nextpage.aspx")
        }else{
        Label1.Text = DateTime.Now.ToLongTimeString();
        }
    }

Please suggest me a solution