The calculated distance (air line) between Diekholzen and Mönchengladbach is approximately 162 miles respectively 260 kilometers.
By car or train, the actual journey to Mönchengladbach is certainly longer, as only the direct route (as the crow flies) between Diekholzen and Mönchengladbach has been calculated here.
Air line (approximately)
260 kilometers
141 nautical miles