Answer:
No, CREs usually don't account for differences in gene expression levels.
Explanation:
<em>Cis</em>-regulatory elements (CREs) are non-coding DNA regions that regulate adjacent gene <em>transcription</em>. They usually do it by binding to transcription factors. They are in charge of influencing the rate of which transcription occurs, and less with how much a gene is expressed. On the other hand, trans-regulatory elements are DNA sequences that encode for upstream regulators that can modify or regulate <em>gene expression levels</em>.
Therefore, cis elements are not really in charge of expression levels, mostly transcription rates of single genes, rather. Trans elements are more involved in expression levels.
RNA: AUGGUACCUUAAUGA
A=U (in RNA only. T in DNA)
C=G (in both DNA and RNA)
"Diabetes" is one of such diseases which cause an imbalance of the blood glucose levels.
Hope this helps!