Detection of microalbuminuria is important in the management of diabetic patients since it is predictive of development of proteinuria and nephropathy. Two sensitive and specific in-house ELISAs for microalbuminuria were established and validated. One of the ELISAs was based on antigen coating while the other employed antibody coating. Recovery and linearity experiments gave acceptable results of 100 +/- 10%, while precision results were <10% for intra-assay and <12% for inter-assay coefficients of variation (CVs). The standard curve ranged from 10-625 ug/l, equivalent to 0.2-12.5 mg/l for urine samples diluted 1:20 fold. When the antibody coated ELISA was compared to antigen coated ELISA, a correlation of r=0.996 was obtained. When compared to commercial kits, the in-house ELISAs gave good correlations of r=0.961 versus the Boehringer Mannheim Micral Test strips and r=0.940 versus Ames Microalb Turbidimetry. The normal microalbumin reference ranges determined for 12h, first morning and random urine samples were 0.7-5.3 mg, 0.1-10.2 mg/l and 0.8-26.1 mg/l respectively. The normal albumin excretion rate (AER) was 1.0-7.3 ug/min while untimed urine samples gave results of 0.1-0.9 and 0.2-1.6 mg/mmol after dividing by creatinine concentrations. The ELISAs were used to detect microalbuminuria in 338 random urine samples from diabetic patients. A high percentage 47.9% was found to be positive for microalbuminuria and 18.0% had macroalbuminuria >25 mg/mmol. Thus screening for microalbuminuria together with creatinine measurements using random urine samples can be used for management of diabetic patients.
Matched MeSH terms: Diabetes Mellitus, Type 1/urine*
We successfully developed an in-house, competitive enzyme immunoassay to measure advanced glycosylation end-products (AGE) in serum. The assay involved coating microtitre wells with AGE-BSA at 8 micrograms/ml for 4 hours, followed by overnight incubation of 20 microliters sample (prediluted at 1:6) with 80 microliters antiserum (1:8000). HRP-labelled goat anti-rabbit was used as the second antibody and 3,5',5,5'-tetramethylbenzidine dihydrochloride as the substrate. Incubation was carried out at 4 degrees C. As suggested in an earlier study, we standardised the AGE units against normal human serum (NHS). Thus, one AGE unit was defined as the inhibition that resulted when the 1:6 diluted NHS was assayed. Mean (+/- SD) AGE level in normal subjects (n = 37) was significantly lower than in diabetes subjects with microalbuminuria (n = 57) (6.0 +/- 0.7 versus 10.2 +/- 4.7 units/ml, p = 0.0001). With the availability of in-house assay and by standardising the AGE unit with the other laboratories, more studies could be undertaken and results compared, and possibly, further elucidate the roles of AGE in the pathogenesis of diabetic complications.
Matched MeSH terms: Diabetes Mellitus, Type 1/urine
This cross-sectional study looked at the prevalence of microalbuminuria and retinopathy in a cohort of 926 young, Type 1 and Type 2 diabetes mellitus (DM) patients, and determined the factors which were associated with these microvascular complications. The prevalence of microalbuminuria, defined as the albumin:creatinine ratio > or = 2.5 (for males) or > or = 3.5 mg/mmol (for females), was 13.4% in Type 1 DM, 69.5% in insulin-requiring Type 2 DM and 16% in Type 2 DM treated only with oral hypoglycemic agents. Compared to those with normal renal functions, these patients were older (P < or = 0.01), had significantly elevated blood pressures (P < 0.01 or P = 0.0001), and in the case of Type 1 DM, with a higher body mass index (P = 0.0001) and waist-hip ratio (P < 0.01). The prevalence of diabetic retinopathy in Type 1 DM was found to increase with the duration of diabetes, from 1.4% in the newly-onset (< 5 years), to 9.9% in those with 5-10 years disease, to 35% among patients with more than 10 years of diabetes (P < 0.0001). In this study, it was also observed that 10% of the Type 2 DM patients already had retinopathy within 5 years of diagnosis, and the prevalence increased significantly to 42.9% (P < 0.0001) among patients who had been diabetics for more than 10 years. Stepwise multiple regression analysis showed that besides the disease duration, systolic blood pressure was the most common and significant determinant for both microalbuminuria and retinopathy in both types of DM, thus implying that in order to reduce the risk of microvascular complications in diabetes mellitus, systolic and not just the diastolic blood pressure, should be effectively controlled.
Matched MeSH terms: Diabetes Mellitus, Type 1/urine