Ionic 2 : Refresh tabs view after adding a new dynamic tab

Try triggering change detection manually –

import { Component, NgZone } from '@angular/core';
import { Events } from 'ionic-angular';
import { DatabaseService } from "../../providers/database.service";

import { ItemsPage } from '../items/items';
import { ContactPage } from '../contact/contact';
import { HomePage } from '../home/home';
import { CategoryPage } from '../category/category';

@Component({
  templateUrl: 'tabs.html'
})
export class TabsPage {

  categories: any = [];

  tab1Root = HomePage;
  tab2Root = CategoryPage;
  tab3Root = ItemsPage;
  tab4Root = ContactPage;

  constructor(public databaseService: DatabaseService, public events: Events, private ngZone: NgZone) {
      this.events.subscribe('category:created', () => {
      this.refreshTabs();
    });
  }

  ngOnInit() {
    this.refreshTabs();
  }

  refreshTabs() {
    this.databaseService.getCategories().then(categories => {
    this.ngZone.run(() => {
      this.categories = categories;
      console.log(this.categories); // [Object, Object, Object]
    });
  });
  }

}