I do have unexplained tiredness and have had several trials of different insulins, and to be perfectly frank I remember becoming intensely more aware of the tiredness when I became a guinea pig for human insulin at the Institute of Child Health, London in 1981. Perhaps going from ox insulin (since 1974 aged 5) to human, triggered something in my body?
There is an account of another user on the forum who experienced relief of his tiredness after switching from human to porcine insulin. However, he experienced strong resistance from his doctor, who was unwilling to prescribe 'inferior' animal insulin over the 'superior' human insulin.
A summary of current research into long term tiredness in T1 diabetics is here..
Google search ncbi, PMC2905388
(Link cannot be posted due to forum policy)
Notice that though there is a lot of speculation about varying glucose levels, etc NOBODY really knows and NOBODY is even thinking of the individual patient response to the specific type of insulin prescribed.
Yet, from the various accounts available here, including yours, the type of insulin seems to be a factor.
Every insulin is actually a uniquely different kind of molecule/drug which tends to mimic the response of your natural hormone. We standardise the preparations to a common efficacy expressed in terms of Insulin Units. But this is based on assumptions as to how the particular drug affects humans...there is place for individual variation. So a particular type of insulin may 'suit' you more than the other despite both being theoretically identical in effect. However the doctor would prefer to prescribe the insulin type which has the least possible long term side effects... So human would be preferable to porcine. Yet human insulin might be less effective in the patient due to individual variation. So even though we think we have given a better drug, its efficacy may be less leading to low energy and tiredness over the long term.
This could possibly be overcome by increasing the insulin dosage slightly over the recommended one...but that would have to be offset by also increasing the dietary intake to avoid low BS. The other option would be to switch the type of insulin... this is what many have reported in practice.
To be sure, long term tiredness is NOT an intrinsic part of being T1 as only some report it, others have no such symptoms at all, despite being diabetic for longer.
What is actually needed is a research study...we need to ask all T1s about tiredness and find the common factor.