I see the big challenge of things like this being the 'pain' in keeping it filled out. I'd love to keep a diet journal myself, but I just can't be bothered. You have to twist my arm to do my expenses with work and this gives me money.

Does it have ways to make maintenance of the diary easy? 

Hey Mick,

 I feel your pain, it was one of the main reasons I started SugarStats.  My goal was to try and make it as easy as possible, but at the same time at the end of the day it really comes down to your habits, your lifestyle and personal determination.  But overall I personally think having it accessible from any web browser and input support from mobile phones/email  is magnatudes better for personal management than pen/paper logs or excel spreadsheets if you're on  the internet regularly.  

Really the only thing you have to  'maintain" is daily entry input for what you want to track (i.e: glucose levels, med entries, food intake, physical actvity, you can customize this.  If all you want is an online glucose log that is fine!), when you log in you're taken to the current day. Almost the entire rest of the system is about aggregating and gather statistics, trends and graphs from the sum of those single days in timelines you can easily understand.

As for cost, its free! The majority of the feature set is included in the free plan and always will be.  The premium plan was crafted based on our surveys and internal statistics and adds a lot of "convenience" features for those out there who want them (added things to be able to track, no ads, ssl encryption etc.).  And even then its about the cost of a starbucks coffee now-a-days anyway.