Updated

Adult diapers are set to outsell baby diapers in Japan by 2020 in just the latest example of the challenges facing a nation where more than 20 percent of the the population are 65 and older.

The Nikkei newspaper reports that paper companies - Daio and Nippon Paper - are expanding their "incontinence products" manufacturing facilities in preparation for an expected surge in demand.

Quartz.com says the adult diaper market is growing by up to 10 percent year-on-year and rakes in $1.4 billion per year - they can go for as much as two and half times the price of baby diapers.

Japan has one of the fastest-aging populations in the industrialized world and there are concerns about how elderly citizens relying on care will be be cared for in the years ahead.

In a startling statistic reported by the Telegraph newspaper, nearly a quarter of all shoplifting arrests in Tokyo last years involved pensioners over the age of 65.

More than 3,320 pensioners were detained by police, eclipsing for the first time the number of teenagers detained in the same year (3,195).

About 70 percent of the thefts involved food, signaling the growing poverty amongst pensioners living alone in Tokyo.

Click for more from news.com.au.