What you haven't said (and nobody so far has asked) is if you have any of the indicators which suggest that you might be at a higher risk of developing diabetes, apart from a close relative having or developing it. Or if your twin has any of these indicators where you don't.
These include:
age (well, yes, you and your twin are likely to have this in the same amount

)
racial origins (for example, some indicators which are 'normal' for a European may be 'high' for an Asian)
weight above the top end of normal BMI,
a waist measurement (true measurement around the belly button not trouser waistband size) of more than twice your height,
lack of general fitness,
a diet heavy in carbohydrates and especially heavy in sugar,
high blood pressure
Your fasting BG over night looks to be inching towards pre-diabetes but without knowing what it was over the last 5 years there is no way to tell if it is on an upward trend or just the way your body works.
Remember that the ranges quoted are only a guide. If you are in the middle of all of them then it is reasonable to suppose that you are normal in your BG regulation.
If you are at the edge of a range then you are more likely to have an issue.
Realise that there isn't a magic switch where one day you are entirely normal and the next day you have a problem just because a value has increased by one decimal point.
Like weight - a BMI of 25 is the top of the 'normal' range.
[Please ignore the edge cases for people who have a non-standard body composition which falls outside the 'normal' as used for BMI.]
You don't put on a pound and become 'fat' then take off two pounds and become 'slim'.
At that weight you are surfing the boundary between "average not at risk" and "average at risk".
Middle of the range is much safer.
So as suggested it is wise to ask for an HbA1c test to see if your long term BG is well into the middle of 'normal' or if it is at the top end of 'normal' and close to pre-diabetes.
That will give you some guidance, and either reassurance or the golden opportunity to nip any problems in the bud before damage is done.
From the parent site to this forum:
http://www.diabetes.co.uk/pre-diabetes.html
"
Testing for prediabetes
Either a
fasting plasma glucose test or an
HbA1c test may be used to diagnose type 2 diabetes or prediabetes.
The following results indicate the presence of prediabetes:
- Fasting plasma glucose: 5.5 mmol/L to 6.9 mmol/L
- HbA1c: 42 to 47 mmol/mol (6.0 to 6.4%)
If your results are above the upper limits for prediabetes, your GP may either diagnose you with type 2 diabetes or take another test in the near future to confirm whether you have diabetes.
"
As you can see, your fasting BG fall within this range.
As an aside, I had a blood test as part of a health check with BUPA (paid for by work) the year before I was diagnosed, which was flagged with BG being a potential issue.
My GP had me tested and said "no, you look to be non-diabetic".
That was seven years ago and perhaps at the time there was less focus on pre-diabetes and the opportunity to treat before full blown diabetes developed.
The practice was a very good diabetes aware practice and were very good indeed with my initial treatment.
Anyway, get yourself checked if only for your own peace of mind.
The fact that your twin is undergoing testing should be more than enough justification for your GP to check you as well.
Hope this helps.
LGC