VARIABLE GLYCATION OF SERUM-PROTEINS IN PATIENTS WITH DIABETES-MELLITUS

Objective: To determine whether there were variations in vivo and in v itro in the glycation process among patients with diabetes mellitus an d to assess the characteristics of patients with high and low glycatio n, if this was observed.Patients: Patients (n = 185) attending a Diabe tes Day Care Centre or Notre-Dame Hospital in Montreal participated in the in vivo study. Patients found to have high and low glycation were asked to allow the use of their serum for the in vitro part of the st udy. Intervention: Capillary blood glucose levels were determined by n ursing staff 4 times a day over 7.3 (standard deviation [SD] 5.3) cons ecutive days with commercially available glucose oxydase reagent strip s and meters. The ratio of the fructosamine concentration to the prote in concentration (the F/P ratio) and the glycated hemoglobin were also determined at the same lime as the capillary blood glucose level. Gly cation was defined as the mean capillary blood glucose/F/P ratio. Pati ents with high and low glycation (higher or lower than 1 SD of the mea n) were compared. For the in vitro study, incorporation of carbon-14 g lucose in serum proteins incubated with a 30-mmol/L glucose concentrat ion was stud led in some of the patients with low and high glycation. Results: The mean capillary blood glucose/F/P ratio was a mean of 2.30 (SD 0.29) g/mL. Of the 185 subjects, 31 had high glycation (1.46 [SD 0.19] g/mL) and 27 had low glycation (2.97 [SD 0.035] g/mL, p < 0.001) . There was no significant difference in age, sex, diabetic treatment and glycated hemoglobin levels between the 2 groups. However, patients with low glycation had a greater body mass index (29.4 [SD 5.7] kg/m( 2) v. 26.4 [SD 4.3] kg/m(2), p < 0.05). In vitro, incorporation of C-1 4 glucose in serum proteins incubated with a 30-mmol/L glucose concent ration was higher in the serum of the 9 patients with high glycation t han in that of the 7 with low glycation (0.031% [SD 0.03%] per gram of proteins v. 0.028% [SD 0.03%] per gram of proteins, p < 0.02). Conclu sions: Glycation may vary among patients with diabetes mellitus who ha ve similar capillary blood glucose concentrations. Glycation appears t o be lower in patients with a greater body mass index. Furthermore, er e alteration in the glycation process itself may explain, in addition to the mean blood glucose level, the difference in fructosamine levels .