A study of exercise-induced microalbuminuria in type I (insulin-dependent) diabetes mellitus

Exercise-induced albuminuria is related to metabolic syndrome

Microalbuminuria (MA) is a known marker for endothelial dysfunction and future cardiovascular events. Exercise-induced albuminuria (EiA) may precede the appearance of MA. Associations between EiA and metabolic syndrome (MS) have not been assessed so far. Our aim was to investigate this association in a large sample of apparently healthy individuals with no baseline albuminuria. This was a cross-sectional study of 2,027 adults with no overt cardiovascular diseases who took part in a health survey program and had no baseline MA. Diagnosis of MS was based on harmonized criteria. All patients underwent an exercise test (Bruce protocol), and urinary albumin was measured before and after the examination. Urinary albumin-to-creatinine ratio (ACR) values before and after exercise were 0.40 (0.21–0.89) and 1.06 (0.43–2.69) mg/g for median (interquartile range) respectively. A total of 394 (20%) subjects had EiA; ACR rose from normal rest values (0.79 mg/g) to 52.28 mg/g after exercise ( P < 0.001); this effect was not shown for the rest of the study population. EiA was related to higher prevalence of MS (13.8% vs. 27.1%, P < 0.001), higher metabolic equivalents ( P < 0.001), higher baseline blood pressure ( P < 0.001), and higher levels of fasting plasma glucose, triglycerides, and body mass index ( P < 0.001). Multivariate binary logistic regression model showed that subjects with MS were 98% more likely to have EiA (95% confidence interval: 1.13–3.46, P = 0.016). In conclusion, EiA in the absence of baseline MA is independently related to MS.

How to predict nephropathy in type 1 diabetic patients

OBJECTIVE

Do exaggerated increases in blood pressure and albuminuria during exercise occur earlier than microalbuminuria and which type of test is most predictive of diabetic nephropathy?

MATERIAL AND METHODS

A total of 33 insulin-dependent normoalbuminuric men (mean duration of diabetes 14 years; mean age 28 years) and 34 age-matched apparently healthy control subjects were studied. Urinary albumin excretion, heart rate and blood pressure were measured during fixed workload (150 W) and fixed heart rate (155 beats/min) tests. Mean follow-up time was 13.1 +/- 3.2 years. A urinary albumin level in early-morning urine persistently >30 mg/l was considered a sign of diabetic nephropathy.

RESULTS

Sixteen patients reached the endpoints of the study. Eleven had developed microalbuminuria and five macroalbuminuria (persistent levels of urinary albumin >300 mg/l). Of the latter patients, two needed dialysis. Systolic blood pressure and albumin excretion during the fixed heart rate test were higher in diabetic patients who developed signs of nephropathy than in control subjects and diabetic subjects with persistent healthy kidneys. Such differences were not found in the fixed workload test. There were no differences in glycated haemoglobin, blood pressure levels or albumin excretion at baseline between the two diabetic groups.

CONCLUSIONS

To predict the development of diabetic nephropathy it seems important to choose a fixed heart rate test. High levels of systolic blood pressure in such a test were associated with the development of micro- and macroalbuminuria.

Lisinopril reduces postexercise albuminuria more effectively than atenolol in primary hypertension

Physical exercise causes transient albuminuria. The mechanisms of postexercise albuminuria are not fully clarified but stimulation of the reninangiotensin system (RAS) probably plays a major role through intrarenal haemodynamic changes causing an elevated filtration pressure. In a randomised, double-blind, crossover study we compared the effects on urinary albumin excretion (UAE) of lisinopril (L) and atenolol (A) therapy, i.e. we aimed to investigate whether inhibition of the RAS or inhibition of beta1-adrenoceptor-mediated effects of the sympathetic nervous system differed with regard to changes in UAE. Sixteen patients with uncomplicated primary hypertension were studied. Four standardised bicycle ergometer exercise tests were performed, before and after each active treatment period. UAE 30 min postexercise, determined by radioimmunoassay, was significantly lowered by both treatments: -278 mu g center dot min-1 (L) and -199 mu g center dot min-1 (A). The reduction of postexercise UAE achieved by treatment with the angiotensin-converting enzyme (ACE) inhibitor (L) was significantly greater than that achieved by the beta1-selective adrenoceptor blocker treatment. Blood pressure (BP) at rest and during exercise were equally reduced by both drugs. In conclusion, this study showed that antihypertensive treatment with an ACE inhibitor was more effective in reducing exercise-induced albuminuria than a beta1-selective adrenoceptor-blocking agent with a similar degree of BP reduction in patients with uncomplicated primary hypertension. This suggests that the RAS plays a major role in postexercise albuminuria in hypertensive subjects. The clinical significance of this finding, however, remains to be clarified.

Voluntary exercise improves glycemia in non-obese diabetic (NOD) mice

The non-obese diabetic (NOD) mouse was used to investigate the effects of voluntary wheel running exercise on blood glucose levels, glycosylated hemoglobin, and longevity in Type 1 diabetes mellitus. In Experiment 1, diabetic and normoglycemic mice exercised 5 h/day, 5 days/week for 3 weeks matched with non-exercising controls. In diabetic animals a positive correlation was found between blood glucose and the number of revolutions performed (P < or = 0.02). Exercise also significantly lowered blood glucose between baseline and post-exercise in both diabetic and normoglycemic animals. In Experiment 2, mice exercised 2 h/day, 5 days/week. For the diabetic animals, glycosylated hemoglobin was lower than that of matched non-exercising diabetic animals at week 3 (11.1 +/- 0.6% vs. 15.0 +/- 1.6%, P < 0.001). Diabetic runners were able to train and significantly increased running in the first 4 weeks (P < 0.05). At the end of 9 weeks all 5 diabetic runners were alive, compared with 3 of 5 non-running diabetic animals. We conclude: (i) the NOD mouse is a useful model for the study of exercise in Type 1 diabetes, (ii) running exercise is associated with a drop in blood glucose, (iii) the amount of voluntary exercise performed correlates with blood glucose in diabetic animals, and (iv) diabetic mice will increase running distance in the first few weeks after diagnosis.

Day and night variation in ambulatory blood pressure in type 1 diabetes mellitus with nephropathy and autonomic neuropathy

The objective was to study ambulatory blood pressure and heart rate variability between day and night in patients with type 1 (insulin-dependent) diabetes mellitus with different degrees of diabetic nephropathy, and to evaluate the influence of autonomic neuropathy and type of antihypertensive treatment. Twenty type 1 diabetic patients with diabetic nephropathy and antihypertensive treatment were studied with 24-h ambulatory blood pressure monitoring using an oscillometric method. They were compared with eight insulin-treated diabetic patients with short duration of diabetes (1-5 years) and with 10 apparently healthy subjects. The degree of autonomic neuropathy was evaluated by measuring the RR-interval during deep breathing and uprising. The 24-h blood pressure was generally higher in patients with diabetic nephropathy compared to those other two groups. These patients also had a lower ratio between day and night in diastolic blood pressure compared to the control subjects (1.15 +/- 0.12 vs. 1.25 +/- 0.76, P < 0.05) and heart rate compared to the diabetic patients without nephropathy, as well as the control subjects (1.15 +/- 0.08 vs. 1.26 +/- 0.09 vs. 1.27 +/- 0.08, P < 0.01, respectively). All patients with diabetic nephropathy had clinical signs of autonomic neuropathy as judged by RR-interval measurements during deep breathing and uprising.

The predictive value of albuminuria for cardiovascular and renal disease. A 5-year follow-up study of 476 patients with type I diabetes mellitus

A 5-year follow-up study of 476 type I adult diabetic patients previously studied cross sectionally revealed that, during the observation period, 19 patients died and 30 developed cardiovascular or renal disease, such as myocardial infarction (n = 8), cerebrovascular disease (n = 3), amputation (n = 6), and renal insufficiency (n = 13). The patients were registered by one and the most-severe event only. The yearly death rate was 8.0 per 1000, compared with the expected death rate of 2.0 for people with corresponding age and sex in the general population. In patients with renal insufficiency, one also had myocardial infarction, and one had had an amputation. The ages of patients who died, with myocardial infarction, cerebrovascular disease, amputation, or renal insufficiency, were 44.2 +/- 12.7, 41.3 +/- 6.6, 43.7 +/- 13.2, 45.3 +/- 15.7, and 40.8 +/- 9.8 years, respectively. Urinary albumin concentration in a single early morning urine sample was found to be a strong prognostic marker for the development of cardiovascular disease or death. In contrast, age, gender, age at onset and duration of diabetes, levels of blood pressure, serum creatinine, and HbA1c, or presence of hypertension, as well as changes in blood pressure and hBa1c, during the observation period did not influence the survival or incidence of cardiovascular disease. However, blood pressure and HbA1c were associated with increased urinary albumin concentrations during the follow-up period.

Type I diabetic nephropathy: clinical characteristics and economic impact

Approximately one-third of type I diabetic patients develop diabetic nephropathy with confounding pathogenesis--frequently manifested as heavy persistent proteinuria, fall in glomerular filtration rate, and increased arterial hypertension. There is increasing incidence and prevalence of type I diabetes, particularly in northern Europe and the United States. Increased morbidity and mortality occur in type I diabetic patients with renal disease. Among type I patients with persistent proteinuria, death occurs on the average within 5-10 years. The economic impact of endstage renal disease due to diabetic nephropathy is overwhelming, and the cost is increasing at an alarming rate.