Increment of 30-min post-challenge plasma glucose is associated with urine albumin excretion in men with normal glucose regulation

Baroreflex function and postprandial hypotension in older adults

PURPOSE

Postprandial hypotension (PPH) is a common but poorly understood etiology for fainting in older adults. One potential mechanism is age-related baroreflex dysfunction. We examined baroreflex function in older adults with PPH and without PPH (noPPH) during a standardized meal test.

METHODS

57 adults (age ≥ 65; 24 PPH, 33 noPPH, mean age 77.9 ± 0.9 years, 54% female) were recruited and had meal tests performed. The baroreflex effectiveness index (BEI, %) and baroreflex sensitivity (BRS, ms/mm Hg) were calculated using the sequence method.

RESULTS

Baseline BEI (22 ± 2 versus 23 ± 2 percent, t = - 0.411, p = 0.682) and BRS (14.1 ± 2.4 versus 13.8 ± 2.5 ms/mm of Hg, t = - 0.084, p = 0.933) were similar in PPH and noPPH subjects. During the meal test PPH subjects showed significantly lower BEI as compared to noPPH subjects (time × PPH, F = 2.791, p = 0.042), while there was no difference in the postprandial change in BRS (time, F = 0.618, p = 0.605).

CONCLUSION

Patients with PPH demonstrated an acute postprandial decrease in baroreflex effectiveness during meal testing as compared with normal subjects, suggesting a potential contributing mechanism for this condition.

Impact of glucose load in an oral glucose tolerance test on urinary albumin excretion varies with 2-h glucose levels

BACKGROUND

The aim of the present study was to investigate whether an oral glucose load can induce an increase in urinary albumin excretion (UAE).

METHODS

One hundred and thirty subjects without macroalbuminuria or increased fasting serum glucose (≥7.0 mmol/L) were included in the study. At 0600 hours, subjects were asked to empty their bladder and drink 300 mL water. At 0800 hours, venous blood and 2-h urine were collected for fasting examination. Subjects were then asked to drink 300 mL solution containing 75 g glucose and, at 1000 hours, samples were collected again for post-challenge examination. Concentrations of serum glucose, urinary glucose, albumin, N-acetyl-β-D-glucosaminidase and retinol-binding protein were measured.

RESULTS

Based on the results of the oral glucose tolerance test, subjects were divided into three groups: (i) normal glucose tolerance (NGT; n = 55); (ii) impaired glucose tolerance (IGT; n = 39); and (iii) newly diagnosed diabetes mellitus (NDM; n = 36). In the NDM group, post-challenge urinary excretion of glucose and albumin was 14- and 1.6-fold greater than fasting values, respectively. In the IGT and NGT groups, although post-challenge urinary glucose excretion was 2.6- and 1.6-fold greater than fasting values, UAE did not increase. There was a positive correlation between post-challenge serum glucose and the UAE rate (UAER; r = 0.24, P < 0.01) and the UAER increment (ΔUAER; r = 0.19, P < 0.05), as well as between the serum glucose increment and post-challenge UAER (r = 0.23, P < 0.01) and ΔUAER (r = 0.18, P < 0.05). Post-challenge serum glucose levels were independently correlated with logarithmically converted post-challenge UAER (β = 0.322, P = 0.008).

CONCLUSIONS

Oral glucose load can induce a significant increase in UAE in NDM subjects. The main mechanism may be glomerular hyperfiltration.