Here is the code to use radio button in C# using SQL.

           if (radioButton1.Checked == true || radioButton2.Checked == true)
            {
                if (radioButton1.Checked == true)
                {
                    savecom.Parameters.AddWithValue("@Sex", "Male");
                }
                else
                {
                    savecom.Parameters.AddWithValue("@Sex", "Female");
                }
            }
            else
            {
                savecom.Parameters.AddWithValue("@Sex", null);
            }

Always use the else case otherwise error shall be come during testing.