They stopped at the chemist around the corner from their flat to fill the scripts Sarah had given him. John also picked up some other things that he didn't have a script for, but knew he would need, like glucose tabs and food.
Sherlock supposed the food would be good, considering what they had in their fridge was mostly limited to non edible experiments.
John dumped his supplies on the kitchen table when they got back, Sherlock marvelling at the goodies. John must have noticed the glint in his eye because he killed any plans before they even could develop.
"No touching anything. Not yet anyway. Got it Sherlock?"
Sherlock scowled, but nodded. It would be enough for now to learn.
He studied John's movement as he pulled a strip out of a container and stuck it in a meter similar to the one Sarah had, except as John had said, much smaller and more efficient. He watched as John diligently went through the process of checking to make sure the strips were good, testing with a control solution before pricking his own finger to squeeze out a drop of blood. Sherlock waited with bated breath as it counted down from five, and not the hundreds or so that the other meter had taken. John held it up for him to see when it was done.
"See, improving."
Sure enough, the number was now 16.4, a far cry from what it had been before.
"What's normal?"
John shrugged. "I'm not sure exactly, but around five."
Sherlock grabbed the pamphlets John had thrown on the table along with everything else and skimmed them.
"4.4 to 6.1," he declared.
John nodded. "Still a ways to go, but headed in the right direction. I'll check it again before I go to bed."
Sherlock frowned. "How often are you going to have to do that?"
John shrugged. "It really depends. At least three times a day. Before I eat, before I go to bed, before I go on a ridiculous chase with you, any time I feel funny. I can't say."
Sherlock sat back, pondering that.
"You know, this is seriously going to interfere with my work," Sherlock sighed.
John snorted. "Right. That's what I was worried about."
They spent the rest of the evening lounging around, watching crap telly and doing research, more on Sherlock's part than John. John was content to just watch telly, leaving Sherlock scouring the net for different treatments and technologies for diabetes. He was extremely disappointed that there was no cure, and made a note to bother Mycroft about that next time he 'stopped by', which was probably going to be as soon as he heard the news.
John went to bed early, still tired, and Sherlock scrutinized him as he tested again, repeating the same process as before.
"13.9," he informed Sherlock, like he couldn't read it himself. "Getting there." He pushed back from the table with a yawn. "I'm going to bed now. Make sure I'm up by nine. I slept through my alarm yesterday."