The levels of glycated hemoglobin were measured using the mini-column method (Isolab
[Quik-Sep], Akron, OH, USA) from 1980 to 1981, the glycospec method (Abbott [ABA-200],
North Chicago, IL, USA) from 1982 to March, 1983, and high-performance liquid
chromatography (HPLC; A8120, HA8121, HA8131, HA8150, HA8160, HA8180: ARKRAY, Kyoto, Japan)
from April, 1983 to the present. The values by the mini-column method [x1] and the
glycospec method [x2] were converted to HPLC [y] values using the following formulae: [y]
= ([x1] + 0.302)/1.179 [r = 0.990] and [y] = ([x2] + 2.151)/1.332 [r = 0.855]. Finally,
all values were expressed as glycated hemoglobin A1c (HbA1c) values (%) as certified by
the National Glycohemoglobin Standardization Program (NGSP) (8 (link)). Systolic blood pressure was measured after resting for five minutes
or longer at the outpatient clinic during each visit since baseline.
The annual mean HbA1c values and systolic blood pressure were calculated, and in
addition, the mean values during the follow-up period were calculated. The urinary protein
levels were semi-quantified using Albustix (Miles-Sankyo, Tokyo, Japan). Patients with
protein in their urine on three consecutive visits were regarded as having proteinuria.
Diabetic retinopathy was diagnosed by ophthalmologists through dilated pupils.
[Quik-Sep], Akron, OH, USA) from 1980 to 1981, the glycospec method (Abbott [ABA-200],
North Chicago, IL, USA) from 1982 to March, 1983, and high-performance liquid
chromatography (HPLC; A8120, HA8121, HA8131, HA8150, HA8160, HA8180: ARKRAY, Kyoto, Japan)
from April, 1983 to the present. The values by the mini-column method [x1] and the
glycospec method [x2] were converted to HPLC [y] values using the following formulae: [y]
= ([x1] + 0.302)/1.179 [r = 0.990] and [y] = ([x2] + 2.151)/1.332 [r = 0.855]. Finally,
all values were expressed as glycated hemoglobin A1c (HbA1c) values (%) as certified by
the National Glycohemoglobin Standardization Program (NGSP) (8 (link)). Systolic blood pressure was measured after resting for five minutes
or longer at the outpatient clinic during each visit since baseline.
The annual mean HbA1c values and systolic blood pressure were calculated, and in
addition, the mean values during the follow-up period were calculated. The urinary protein
levels were semi-quantified using Albustix (Miles-Sankyo, Tokyo, Japan). Patients with
protein in their urine on three consecutive visits were regarded as having proteinuria.
Diabetic retinopathy was diagnosed by ophthalmologists through dilated pupils.