what was the three most frequent specimen tests that patients had within the same month after being diagnosed with abnormal glucose nec until 2101?
select t3.spec_type_desc from ( select t2.spec_type_desc, dense_rank() over ( order by count(*) desc ) as c1 from ( select admissions.subject_id, diagnoses_icd.charttime from diagnoses_icd join admissions on diagnoses_icd.hadm_id = admissions.hadm_id where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'abnormal glucose nec' ) and strftime('%y',diagnoses_icd.charttime) <= '2101' ) as t1 join ( select admissions.subject_id, microbiologyevents.spec_type_desc, microbiologyevents.charttime from microbiologyevents join admissions on microbiologyevents.hadm_id = admissions.hadm_id where strftime('%y',microbiologyevents.charttime) <= '2101' ) as t2 on t1.subject_id = t2.subject_id where t1.charttime < t2.charttime and datetime(t1.charttime,'start of month') = datetime(t2.charttime,'start of month') group by t2.spec_type_desc ) as t3 where t3.c1 <= 3