By "needle" I assume you mean the Libre sensor which about the size of a ten pence piece and typically placed under your upper arm. Compared to full CGM such as DexCom, the Libre sensor is small. They have not changed the size. You can see this (and more information) on the Freestyle Libre
website
There are lots (and lots and lots) of threads about the stickiness of the sensors. I highly recommend reading through some of these threads as everyone's experience is different. For example, over about 2 years, I have used about 15 sensors. The first fell off and was replaced by Abbott. Recently, one other came detached from the sticky backing but the sticky backing remained attached to my arm. Abbott replaced this too. No other sensor has fallen off. Prolonged periods in water (such as swimming) may loosen the sensor. I have no experience of this but may be something experienced by the lady on your cruise. Some people attach something like Tagaderm to give extra stickiness insurance.
I have read, due to a high volume of reactions to the stickiness, Abbott are soon changing the stickiness they use.
Abbot advise readings may be less accurate during the first 24 hours. Therefore, quite a few people will attach their sensor for 24 hours before activating it. If they have another on, they will have two sensors attached at the same time overnight.
No sensor is as accurate as finger pricks especially outside the "acceptable" range so if the sensor reports readings higher than 7 or lower than 4, I will
always check with a finger prick and often check sensor readings before dosing insulin.
The Libre is not a replacement for finger pricks. The value of the Libre is the trends it provides it is not the moment in time readings.
