Firstly, don't lose sight of the fact that you have been diagnosed diabetic and you won't fix that overnight so whilst you are only just over the threshold into diabetes territory, your levels will be at the higher end of that range or slightly above sometimes for a few weeks until the steps you have taken with your diet and hopefully exercise will start to take effect, so don't be deflated or anxious about that 7 or 7.5, they just indicate what we already know which is that you have diabetes, but you are taking steps to deal with that, so these readings are just charting the start of your journey. I would anticipate that in a few weeks/months you are getting 6s or hopefully 5s for your morning reading as the lifestyle changes take effect. Morning readings are usually the last to come down into better numbers, so don't be disheartened, you will start to see this slowly come down over weeks not a couple of days. My readings were mid teens when I started and sometimes higher, so think yourself lucky you are getting 7s to start. If you were much lower you wouldn't be diabetic.
As has been mentioned there are a lot more things that impact BG than just the food we eat, so it rises and falls throughout the day and night in response to something like 42 different factors, some of which you have control over but many that you don't. Food, exercise and medication are almost certainly the main players which have most impact and you have control over those, so don't worry about the rest. The medication you were offered (Metformin) has pretty minimal effect, so don't spare that any great concern in your case and just focus on the food and exercise.
The reason why we recommend people test just before eating and then 2 hours afterwards is to try to isolate the response we have to that food from other factors which might be changing our levels throughout the day. So, say you wake up at 7am and test before you get out of bed and get a 6.2 and then get up and get washed and dressed and get a coffee and sit down to breakfast half an hour later, your levels might have risen to 7.5 or even 8 by then due to your liver releasing glucose into your blood stream to give you energy to start your day. This is believed to date back to prehistoric times when we had to hunt and/or gather our first meal of the day and without that glucose release we wouldn't have the energy to do so and would quickly starve. Of course it takes very little energy to walk into the kitchen and open a few cupboards and the fridge, so that glucose release on a morning is a bit of a pain for us diabetics, because we are not balancing it properly with insulin and storing it for later. If you were not diabetic your body pancreas would get a message from your liver to say you need to ramp up insulin production to deal with this and your cells would respond to the insulin and store it for later, so your BG levels wouldn't rise, but because this system is faulty at the moment, your levels rise on a morning. This may start in the early hours as it starts to get light at this time of year which is called Dawn Phenomenon or when you get out of bed and stand upright (Foot On The Floor Syndrome). As your body's insulin balance systems improve and your diabetes "gets better" you will see this effect reduce because your body is coping again and your morning levels will come down to more normal numbers in the 4s and 5s.
Anyway, what I am saying is that readings in the 7s at the moment are to be expected because they just tell us what we already know, which is that you are diabetic, but if you stick at the lifestyle changes you can reasonably expect those levels to slowly come down over the next few weeks and months bit by bit. There will be days when they might be a bit higher and days when they are slightly lower because of those other factors which we have little or no control over, but the overall trend will be downwards, so next week you might get the odd reading in the 6s and the week after that you might get most readings in the 6s but the odd 7 and gradually the 7s will be more rare and you will start to see the odd 5. It takes time for your body to heal, but as long as you are generally heading in the right direction, what you are doing is working and you are well on your way.
I am sure you will have experienced the same with weight loss. You might lose weight for a couple of days and then be static or put on half a pound for no obvious reason and then drop again.....Try not to get hung up on the slight blips when it goes in the wrong direction and look at the longer term picture of overall reduction over weeks rather than days.
