SS never stopped considering the effects of diabetes (or any other illness/disease/disorder not included in the Blue Book). That Policy Interpretation Ruling just goes into great detail of how an adult with diabetes can still qualify for SSDI/SSI even though diabetes by itself is no longer a "listed impairment."
There are 3 ways to qualify for SSDI/SSI: 1) meet a listing impairment 2) by the Grid Rules, or 3) the 5 step evaluation process.
If you can ask your attorney which of the three apply to your case, it would be a big help in answering your questions.
So, an adult with diabetes can still meet a listed impairment, if for example, they meet SS's definition of blindness, in the Special Senses Impairment LISTING:
"2.02 Loss of Visual Acuity. Remaining vision in the better eye after best correction is 20/200 or less.
2.03 Contraction of the visual field in the better eye, with:
A. The widest diameter subtending an angle around the point of fixation no greater than 20 degrees;
OR
B. An MD of 22 decibels or greater, determined by automated static threshold perimetry that measures the central 30 degrees of the visual field (see 2.00A6d).
OR
C. A visual field efficiency of 20 percent or less, determined by kinetic perimetry (see 2.00A7c).
2.04 Loss of visual efficiency, or visual impairment, in the better eye:
A. A visual efficiency percentage of 20 or less after best correction (see 2.00A7d).
OR
B. A visual impairment value of 1.00 or greater after best correction (see 2.00A8d).
http://www.ssa.gov/disability/profes...Adult.htm#2_02
That ruling also goes into great detail about how the 5 step evaluation process can be used to qualify for SSDI and gives examples specifically for an applicant with diabetes .
"Assessing Residual Functional Capacity
When the effects of DM, alone or in combination with another impairment(s), are severe but do not meet or medically equal the criteria of a listing, we assess an adult's residual functional capacity (RFC).[10] RFC is the most an adult can do despite his or her limitation(s).
The combined effects of DM and another impairment(s) can be greater than the effects of each of the impairments considered separately. We consider all work-related physical and mental limitations, whether due to an adult's DM, other impairment(s), or combination of impairments. For example, adults with peripheral sensory neuropathy may have difficulty walking, operating foot controls, or manipulating objects because they have lost the ability to sense objects with their hands or feet. Adults with chronic hyperglycemia may experience fatigue or difficulty with concentration that interferes with their ability to perform work activity on a sustained basis.
We then proceed to step 4 and, if necessary, step 5 of the sequential evaluation process. We use the RFC assessment at step 4 to evaluate whether an adult is capable of performing any past relevant work (PRW) as he or she actually performed it or as the job is generally performed in the national economy. If an adult's RFC precludes the performance of PRW (or if there was no PRW), we use the RFC assessment to make a finding at step 5 about his or her ability to perform other work that exists in significant numbers in the national economy. The usual vocational considerations apply.[11]"