I don't understand why you would be told to have a couple of biscuits or having a banana? Telling a diabetic to eat sugar and or fructose before sleeping is plainly wrong.
Although difficult in this hectic life, it is best to eat at least 3 or more hours before you go to bed. In theory your BSL will fall to normal, or as normal as a T2D can be. 6.8 is high and if you are deliberately making yourself higher before sleeping, you might as well be poisoning yourself.
If you are not on a low carb, high fat diet, you should be, and if you can include some time restricted eating, i.e. only eat within a specified time period, starting at say 8 hours and reducing to 4 or less. That will eventually clear you of the sugar in your system activate your body to work of ketones i.e. energy from your internal fat, not insulin creating sugar. If you adopt the aforesaid diet, you will reduce your BSL, and because you are already taking insulin keep monitoring your BSL so that you can reduce and eventually come off insulin as your BSL improves.
Most T2D will usually have a higher BSL in the morning, because it is the body's natural way to prepare you for the day ahead after you wake up. If you poison yourself before you go to bed with sugar, your body will try to clear it within and by the time it does, will then dump sugar back into your system between 4 and 7 am in order to get you ready to wake up. All that you are doing is maintaining a high sugar and insulin state are a time of the day when you cannot regulate it with medication because you are asleep.
If you can start reducing your carb/sugar intake, you will still get a high morning reading, because its natural, but as your body moves over to relying on ketones for energy, that spike will gradually get smaller and smaller. If you continue to consume carbs, then all you will achieve is long term ill health as you dependence on external insulin continues to grow and you develop the complications associated with high insulin levels in the blood (if you haven't already), including obesity, diabetic neuropathy, retinopathy, kidney failure, heart disease, alzheimers, and limb amputations. T2D is in part or in whole reversible by everyone suffering this affliction.