Anaerobic threshold can provoke microalbuminuria in non-insulin-dependent diabetics

Are triplicate urine samples necessary to assess albuminuria?

BACKGROUND/AIMS

Urinary albumin excretion is subject to intra-individual variability. Thus, for research purposes, it is recommended to test three urine samples collected over a short period of time. The objective of our analysis was to check the usefulness of triplicate samples to determine the albuminuric status of diabetic patients.

METHODS

We present the results of the non-planned retrospective analysis of 246 triplicate morning urine samples obtained from 95 type 2 diabetics included in three multinational, randomized, double-blind studies. Albuminuria was determined by immunoturbidimetry on fresh samples in the same central laboratory. Microalbuminuria was defined by a urine albumin to creatinine ratio (UACR) between 2.5 and 25 mg/mmol in males and between 3.5 and 35 mg/mmol in females. Concordance was obtained when the second and/or third sample (UACR2 and UACR3) confirmed the albuminuric status obtained from the first sample (UACR1).

RESULTS

Considering the first samples, 9% were within the normal range, 35% showed microalbuminuria and 56% showed macroalbuminuria. The overall concordance rate was 95%. The log of UACR was highly correlated between samples. Bland-Altman plots expressed in percent variations between two samples confirmed that the mean variation was low (around 8%) but revealed the scattering of values, 95% being between -60 and +77% of variation between samples.

CONCLUSIONS

There is no benefit in repeating morning UACR determination in diabetic patients to accurately categorize a subject as having normo-, micro- or macroalbuminuria. However, in order to accurately quantify albuminuria, repeated determinations are required.

Lactate threshold prediction by blood glucose and rating of perceived exertion in people with type 2 diabetes

The validity of rating of perceived exertion (RPE) in predicting lactate threshold during an incremental test was analyzed in 15 men with type 2 diabetes (M age = 53.4 yr., SD = 12.9). Blood glucose, lactate, and minute ventilation (VE)/VO2 responses identified the lactate, ventilatory, and glucose thresholds. Workloads (W) corresponding to RPEs 12, 13, 14, and 15 were determined. Second-order polynomials fit to VE/W and [lac]/W ratios corresponding to RPEs of 9-10, 12-13, and 16-17 also identified workloads above which there was an overproportional increase in VE and [lac]. These workload breakpoints did not differ, although at RPE 12 underestimated and at RPE 15 overestimated lactate threshold. RPE 13 and 14 and the responses of VE/W and [lac]/W to submaximal exercise accurately predicted lactate threshold.

Cost-sparing effect of twice-weekly targeted endurance training in type 2 diabetics: a one-year controlled randomized trial

OBJECTIVE

We evaluated the effects of targeted, moderate endurance training on healthcare cost, body composition and fitness in type 2 diabetes patients routinely followed within the French healthcare system.

DESIGN AND METHODS

A total of 25 type 2 diabetic patients was randomly assigned to one of two groups: 13 underwent a training programme (eight sessions, followed by training twice a week for 30-45 minutes at home at the level of the ventilatory threshold [V(T)]); and 12 received their usual routine treatment. Both groups were followed for one year to evaluate healthcare costs, exercise effectiveness and a six-minute walking test.

RESULTS

The training prevented loss of maximum aerobic capacity, which decreased slightly in the untrained group (P=0.014), and resulted in a higher maximum power output (P=0.041) and six-minute walking distance (P=0.020). The Voorrips activity score correlated with both V(O2max) (r=0.422, P<0.05) and six-minute walking distance (r=0.446, P<0.05). Changes in V(O2max) were negatively correlated with changes in body weight (r=0.608, P<0.01). Training decreased the insulin-resistance index (HOMA-IR) by 26% (P<0.05). Changes in percentages of fat were correlated to changes in waist circumference (r=0.436, P<0.05). The total healthcare cost was reduced by 50% in the trained group (euro 1.65+/-1 per day versus euro 3.00+/-1.47 per day in the untrained group; P<0.02) due to fewer hospitalizations (P=0.05) and less use of sulphonylureas (P<0.05).

CONCLUSION

Endurance training at V(T) level prevented the decline in aerobic working capacity seen in untrained diabetics over the study period, and resulted in a marked reduction in healthcare costs due to less treatments and fewer hospitalizations.

Lactate and ventilatory thresholds in type 2 diabetic women

Anaerobic threshold (AT) has been considered the optimal exercise intensity for type 2 diabetes mellitus (DM 2) patients, but there is little information about the comparison between lactate (LT) and ventilatory (VT) thresholds in this population, particularly during treadmill exercise. Therefore, we evaluated DM 2 women in order to compare and analyze the relationships between VT and LT intensities. Fifteen women with DM 2 without complications and comorbidities (50.7 +/- 8.0 years; 71.3 +/- 8.6 kg; 154 +/- 5 cm; 37.8 +/- 3.9% fat; 4.7 +/- 3.2 years of disease diagnose and 138 +/- 45 mg/dl fasting glucose) were subjected to a graded treadmill test-initial velocity and increments of 1 km/h every 2 min until voluntary exhaustion. VT was determined from V(E)/V(O(2)) and V(E)-V(CO(2)) ratios and LT was defined as the point at which a first increase in blood lactate occurs during incremental test. Our results showed no significant differences (p > 0.05) and significant correlations between VT and LT expressed in velocity (4.7 +/- 0.7 versus 4.6 +/- 0.7 km/h, r = 0.62), absolute V(O(2)) (1.27 +/- 0.33 versus 1.24 +/- 0.28 l min(-1), r = 0.93); relative V(O(2)) (18.3 +/- 5.7 versus 17.6 +/- 4.6 ml kg(-1) min(-1), r = 0.84) and %V(O(2)(max)) (80 +/- 12 versus 78 +/- 10%, r = 0.82). These results suggest that both VT and LT can be used to access AT in DM 2 women during graded treadmill exercise.

Effect of nitric oxide on exercise-induced proteinuria in rats

Temporary proteinuria occurring after exercise is a common finding, and it is explained predominantly by alterations in renal hemodynamics. In this study, we investigated whether nitric oxide (NO), which is known to have an effect on renal hemodynamics and to increase during exercise, has a role in postexercise proteinuria. In the first step of this study, the effect of acute NO synthase blockage on exercise proteinuria was evaluated. The urinary protein levels in animals that performed acute exhaustive treadmill running exercise were considerably elevated compared with the control animals. Significantly elevated urinary protein levels were also detected in animals that received Nomega-nitro-L-arginine methyl ester before exhaustion, compared with both control and exhausted groups, and mixed-type proteinuria was detected in electrophoresis, as in all exhausted animals. In the second step of the study, a NO donor (isosorbide mononitrate) was given to rats 1 h before exhaustive exercise. Mixed-type proteinuria and the elevation in urinary protein levels that occur as a consequence of exhaustive exercise were prevented by NO donor treatment. Finally, in the third step of our study, a calcium channel blocker (diltiazem), another vasodilator, was applied to the rats 1 h before exhaustive exercise. Urinary protein levels were not different in exhausted rats with or without calcium channel blocker treatment. On the other hand, in both groups, urinary protein levels were higher than in the control group. The tail-cuff blood pressure alterations caused by vasodilator drug applications before exercise were not different for NO donor and calcium channel blocker groups. These results suggest that endogenous NO might prevent the postexercise proteinuria from becoming more severe by affecting hemodynamic changes that occur during exercise.