How to get the default value of radio button from database?
As the radios are separate field in itself, default value should be as easy as follow

foreach ($check-box-options as $key =&gt; $value) {
        //A. A function to query database to get default value
        $default_value = _my_module_helper_get_default_radio_option($key);

        //B. Or if its a system setting form, all values are inside the variables, in that case all you have to do is variable_get()
        $default_value = variable_get('radio_'.$key);

        // Depending on form type use option A or B.

        $form['radio_'.$key] = array(
            '#type' =&gt; 'radios',
            '#title' =&gt; t('abc'),
            '#options' =&gt; $filter_radio_options,
            '#default_value'=&gt; $default_value,
            '#states' =&gt; array(
                'visible' =&gt; array(
                    ':input[name="filter_criteria_options['.$key.']"]' =&gt; array('checked' =&gt; TRUE),
                ),
            ),
        );
}

// In case option A is what you needed.
function _my_module_helper_get_default_radio_option($key) {
  return db_select('your_table','yt')
         -&gt;fields('yt',array('field_name'))
         -&gt;condition('yt.field_is',$key,'=')
         -&gt;exectue()
         -&gt;fetchField();

 }