Hi,
It probably is the high BG's causing you to feel tired and energyless.
When your BG is high pretty much most of your body tries to work overtime to compensate to get rid of the glucose in your system. Few examples;
You body will expel glucose in urine, sweat and saliva. so it's likely you will feel dehydrated and headachy.
Glucose builds around the eyes, causing blurriness and again headaches.
Your heart can sometimes have to work harder to pump the blood around your body.
So as your body is doing all these extra things and more, it's likely to feel tired.
As your BG is high it could be possible your body has turned to breaking down fat for energy if it can't process the glucose in your bloodstream (ketosis)
I can certainly tell if i have had elevated BG's for a little while as i can sleep for england!!! :lol:
Someone maybe along with a more scientific way of explaining things but it's a start
As you get better with your diabetes and start to get your BG's down you will definately start to feel a difference