Abnormal albuminuria and blood pressure rise in incipient diabetic nephropathy induced by exercise

Clinical safety of blood flow-restricted training? A comprehensive review of altered muscle metaboreflex in cardiovascular disease during ischemic exercise

Blood flow restriction training (BFRT) is an increasingly widespread method of exercise that involves imposed restriction of blood flow to the exercising muscle. Blood flow restriction is achieved by inflating a pneumatic pressure cuff (or a tourniquet) positioned proximal to the exercising muscle before, and during, the bout of exercise (i.e., ischemic exercise). Low-intensity BFRT with resistance training promotes comparable increases in muscle mass and strength observed during high-intensity exercise without blood flow restriction. BFRT has expanded into the clinical research setting as a potential therapeutic approach to treat functionally impaired individuals, such as the elderly, and patients with orthopedic and cardiovascular disease/conditions. However, questions regarding the safety of BFRT must be fully examined and addressed before the implementation of this exercise methodology in the clinical setting. In this respect, there is a general concern that BFRT may generate abnormal reflex-mediated cardiovascular responses. Indeed, the muscle metaboreflex is an ischemia-induced, sympathoexcitatory pressor reflex originating in skeletal muscle, and the present review synthesizes evidence that BFRT may elicit abnormal cardiovascular responses resulting from increased metaboreflex activation. Importantly, abnormal cardiovascular responses are more clearly evidenced in populations with increased cardiovascular risk (e.g., elderly and individuals with cardiovascular disease). The evidence provided in the present review draws into question the cardiovascular safety of BFRT, which clearly needs to be further investigated in future studies. This information will be paramount for the consideration of BFRT exercise implementation in clinical populations.

Beneficial effects of previous exercise training on renal changes in streptozotocin-induced diabetic female rats

This study evaluated the effects of aerobic exercise performed both previously and after the induction of diabetes mellitus on changes of renal function and structure in streptozotocin-induced diabetic rats. Female wistar rats were divided into five groups: sedentary control (C + Se); trained control (C + Ex); sedentary diabetic (D + Se); trained diabetic (D + Ex) and previously trained diabetic (D + PEx). The previous exercise consisted of treadmill running for four weeks before the induction of diabetes mellitus. After induction of diabetes mellitus with streptozotocin, the D + PEx, D + Ex and C + Ex groups were submitted to eight weeks of aerobic exercise. At the end of the training protocol, we evaluate the serum glucose, insulin and 17β-estradiol levels, renal function and structure, proteinuria, and fibronectin, collagen IV and transforming growth factor beta 1 (TGF-β1) renal expressions. Induction of diabetes mellitus reduced the insulin and did not alter 17β-estradiol levels, and exercise did not affect any of these parameters. Previous exercise training attenuated the loss of body weight, the blood glucose, the increase of glomerular filtration rate and prevented the proteinuria in the D + PEx group compared to D + Se group. Previous exercise also reduced glomerular hypertrophy, tubular and glomerular injury, as well as the expressions of fibronectin and collagen IV. These expressions were associated with reduced expression of TGF-β1. In conclusion, our study shows that regular aerobic exercise especially performed previously to induction of diabetes mellitus improved metabolic control and has renoprotective action on the diabetic kidney.

Exercise excess pressure and exercise-induced albuminuria in patients with type 2 diabetes mellitus

Exercise-induced albuminuria is common in patients with type 2 diabetes mellitus (T2DM) in response to maximal exercise, but the response to light-moderate exercise is unclear. Patients with T2DM have abnormal central hemodynamics and greater propensity for exercise hypertension. This study sought to determine the relationship between light-moderate exercise central hemodynamics (including aortic reservoir and excess pressure) and exercise-induced albuminuria. Thirty-nine T2DM (62 ± 9 yr; 49% male) and 39 nondiabetic controls (53 ± 9 yr; 51% male) were examined at rest and during 20 min of light-moderate cycle exercise (30 W; 50 revolutions/min). Albuminuria was assessed by the albumin-creatinine ratio (ACR) at rest and 30 min postexercise. Hemodynamics recorded included brachial and central blood pressure (BP), aortic stiffness, augmented pressure (AP), aortic reservoir pressure, and excess pressure integral (Pexcess). There was no difference in ACR between groups before exercise ( P > 0.05). Exercise induced a significant rise in ACR in T2DM but not controls (1.73 ± 1.43 vs. 0.53 ± 1.0 mg/mol, P = 0.002). All central hemodynamic variables were significantly higher during exercise in T2DM (i.e., Pexcess, systolic BP and AP; P < 0.01 all). In T2DM (but not controls), exercise Pexcess was associated with postexercise ACR ( r = 0.51, P = 0.002), and this relationship was independent of age, sex, body mass index, heart rate, aortic stiffness, antihypertensive medication, and ambulatory daytime systolic BP (β = 0.003, P = 0.003). Light-moderate exercise induced a significant rise in ACR in T2DM, and this was independently associated with Pexcess, a potential marker of vascular dysfunction. These novel findings suggest that Pexcess could be important for appropriate renal function in T2DM.

Effects of training and nitric oxide on diabetic nephropathy progression in type I diabetic rats

The aim of the paper is to assess nitric oxide (NO) production during aerobic training and its role on the progression of diabetic nephropathy in rats. Induction of diabetes mellitus (DM) was achieved in adult male Wistar rats with streptozotocin. Half of the animals underwent training on a treadmill and the others (sedentary) stayed on a turned-off treadmill for the same period according to the following groups: sedentary control (CTL + SE); training control (CTL + EX); sedentary diabetic (DM + SE); and training diabetic (DM + EX) (n = 9 for all groups). The training on treadmill was carried out at a work rate of 16 m/min, 60 min/d, 5 d/week for eight weeks. Before and after the exercises, rats were placed in individual metabolic cages with standard chow and water ad libitum, for 24-h urine collection, followed by three hours' fasting blood sample withdrawal from the retro-orbital plexus, under anesthesia. Diabetic animals showed reduction of body weight, creatinine and urea depurations and NO excretion, increased blood glucose concentrations, albuminuria and thiobarbituric acid reactive substance (TBARS) excretion, when compared with the respective controls. All these alterations induced by DM were attenuated in the DM + EX versus DM + SE group. Analysis of insulin concentrations at the end of the protocol showed no significant change between the DM + SE and DM + EX groups. In conclusion, our data show that a routine physical exercise resulted in a better control of glycemia with an increased NO bioavailability and oxidative stress control, associated with an amelioration of renal function. We suggest aerobic training and the control of oxidative and nitrosative stress as useful non-pharmacological tools to delay the progression of diabetic nephropathy.

Is exercise-induced blood pressure rise predictive of nephropathy in insulin-dependent diabetes?

A follow-up study was performed in 48 male diabetics and 17 age-matched male controls, who in 1963 and 1971 participated in an exercise study to evaluate if the results could predict later development of diabetic nephropathy. The inclusion criteria were: Type I (insulin-dependent) diabetes with age below 40, onset of diabetes before age of 30, duration of diabetes more than 7 years and no proteinuria at the time for the first study. The diabetics demonstrated higher systolic blood pressure (BP) at work but as good physical condition as the controls. Thirteen developed nephropathy after 23 years (range 15-36) of diabetes duration. It was found that exercise-induced, abnormally raised systolic BP was not associated with later development of diabetic nephropathy.

Metabolic and blood pressure monitoring in diabetic renal failure

In a prospective study of eight patients with type I diabetic renal failure, metabolic and blood pressure monitoring was evaluated during progression to end-stage renal disease (ESRD). The mean observation time was 37 months. The mean glomerular filtration rate (GFR) fell significantly (from 33 to 16 ml/min) implying a mean deterioration rate of 0.57 ml/min/month. This rate showed significant correlation with mean arterial blood pressure at out-patient observations, but not with blood glucose monitored as 24-hour profile or with glycosylated hemoglobin. Patients with growth hormone values within the upper limit of the normal range showed faster decline of GFR than patients with low values. The study demonstrated that advanced diabetic renal failure may progress slowly to ESRD. The blood pressure pattern, but not blood glucose values, influenced significantly the deterioration rate of glomerular function.

Association between Cigarette Consumption and Proteinuria in Healthy Japanese Men and Women from an Occupational Population

The association between cigarette consumption and prevalence of mild proteinuria (30-99 mg/dl of albumin) was analyzed in 11,569 male and 4,715 female workers aged 18-67 yr recruited from an occupational population. Proteinuria was found in 274 (2.4%) of the total male workers and in 50 (1.1%) of the total females. Stepwise logistic regression analyses showed that sex, suspected diabetes mellitus, blood pressure (BP) and Brinkman Index (BI) levels (0, 1-199, 200-499, 500-799, 800-) were significantly related to proteinuria, and that the odds ratio of each BI level for proteinuria was 1.11 (C.I.: 1.01-1.67). In the subjects aged 50 yr or older, after excluding those suspected of having hypertension and/or diabetes mellitus, the odds ratio reached 1.37 (C.I.: 1.15-1.63), with the gender difference then no longer significant. The odds ratio for proteinuria was calculated as 5.44 (C.I.: 2.27-13.0) in male and female smokers having a BI of 500 or above and normal-high BP (130-139/85-89 mmHg) in comparison with nonsmokers having normal BP (<130/85 mmHg). These results suggest that heavy cigarette consumption represented by a BI of 500 or above is a risk factor of proteinuria even in healthy Japanese workers, particularly in those aged 50 yr or older and having normal-high BP.

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.

Acute effects of different intensities of exercise in normoalbuminuric/normotensive patients with type 1 diabetes

OBJECTIVE

The purpose of this study was to investigate the effect of exercise occurrence and intensity on albumin excretion in normotensive, normoalbuminuric patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Eighteen patients (aged 29 +/- 2 years, duration of diabetes 14 +/- 2 years, blood pressure 120 +/- 2/74 +/- 1 mmHg, HbA(1c) 7.0 +/- 0.2% [mean +/- SE]) without microalbuminuria, hypertension, or anti-angiotensin II therapy participated in two exercise studies in a clinical research center. Exercise intensities were defined as moderate (50% heart rate reserve [HRR]) and intense (75% HRR) and were performed in random order. Subjects collected urine for albumin determination on the days before and after exercise. On the day of exercise, subjects exercised for 30 min on a treadmill at the assigned intensity. Timed urine collections were obtained over the day. Blood pressures were measured using an ambulatory blood pressure monitor.

RESULTS

Moderate exercise demonstrated no changes in albumin excretion. Intense exercise demonstrated a significant increase in albumin excretion during the first 4 h compared with the rest of the day (P = 0.03) but returned to normal thereafter. Albumin excretion did not exceed normal levels throughout the study. There was no difference in albumin excretion surrounding days of intense exercise. Ambulatory blood pressures demonstrated nocturnal dipping after moderate and intense exercise (P < 0.001).

CONCLUSIONS

We have demonstrated that normotensive, normoalbuminuric patients without anti-angiotensin II therapy do not have elevated albumin excretion following exercise intensities experienced by most patients with type 1 diabetes.

ACE inhibitor intervention in Type 1 diabetes with low grade microalbuminuria

Several clinical trials have consistently shown that antihypertensive treatment, particularly with angiotensin-converting enzyme inhibitors (ACE-I) reduces albuminuria in Type 1 diabetic patients. More recently, data on the beneficial effects of ACE-I on the preservation of glomerular filtration rate and renal ultrastructure have emerged. However, in general, these trials have recruited a wide spectrum of diabetics, including some patients with severe albuminuria. Thus, the question of the ideal stage at which to instigate what is likely to be lifelong therapy in young people still remains unanswered. Exercise is known to significantly increase both blood pressure (BP) and urinary albumin excretion (UAE), both of which are important determinants of progression of nephropathy in diabetes. Thus, it is possible that exercise may have an adverse effect on diabetic renal disease. The effects of ACE-I on exercise-BP and exercise-UAE in microalbuminuric Type 1 diabetic patients has not been examined in long-term placebo-controlled studies. In the second part of this two-part review, we examine the effects of the ACE-I, lisinopril, 20 mg o.d. for two years, in comparison with placebo, on UAE, 24-hour ambulatory BP, exercise-BP, exercise-UAE and renal haemodynamics in 22 patients with Type 1 diabetes and low-grade microalbuminuria. We further discuss the effects of ACE-I on nephropathy and other complications of diabetes.

Lisinopril reduces albuminuria during exercise in low grade microalbuminuric type 1 diabetic patients: a double blind randomized study

BACKGROUND

Antihypertensive treatment is presently recommended in most type 1 diabetic patients with microalbuminuria. The long-term effect of angiotensin converting enzymes (ACE) inhibitor (ACE-i) treatment on exercise urinary albumin excretion (E-UAE) and exercise blood pressure (E-BP) in type 1 diabetic patients with low grade microalbuminuria is not well documented. In addition, the possible predictive effect of baseline E-UAE on the progression of overnight UAE remains to be clarified.

DESIGN AND METHODS

In a randomized placebo controlled double blind study the effects of 2 years treatment with either lisinopril (20 mg o.d.) or placebo was evaluated in 21 normotensive type 1 diabetic patients with overnight UAE between 20 and 70 microg min-1. Determinations of E-UAE and E-BP were performed after exercise on an ergometercycle with a load of 70% of estimated maximal VO2 for 20 min. Patients in the placebo and lisinopril groups were similar with regard to age (35.8 +/- 11.3 vs. 29.3 +/- 8.6 years), duration of diabetes (19.4 +/- 8.2 vs. 16.8 +/- 5.3 years), and HbA1c (9.0 +/- 1.0 vs. 9.4 +/- 1.7%).

RESULTS

At baseline, E-UAE was similar in the two groups (placebo: 150.1 x or divide 3.7, lisinopril: 96.8 x or divide 1.8 microg min-1 (geometric mean x or divide tolerance factor)). After 2 years treatment E-UAE had increased in the placebo group, whereas E-UAE was reduced in the lisinopril treated patients (placebo: 213.6 x or divide 6.9, lisinopril: 48.3 x or divide 3.1 microg min-1, P = 0.04). The relative increase in E-UAE (E-UAE/Pre-exercise UAE) was similar at baseline in both groups (3.7 x or divide 2.3 vs. 2.8 x or divide 2.0) but significantly higher in the placebo group after 2 years (4.4 x or divide 2.4 compared with 1.6 x or divide 1.7 in the lisinopril group, P < 0.01) These changes over two years in relative increase in E-UAE were significantly different (P = 0.03). Exercise blood pressure was similar in both groups at baseline and over 2 years increased in the placebo group (from 166.5 +/- 15.1-179.9 +/- 35.6 mmHg), in contrast to the lisinopril group where E-BP was slightly reduced (from 168.5 +/- 20.6-165.1 +/- 16.6 mmHg) but the difference in blood pressure over the 2 years did not reach statistical significance. Exercise urinary albumin excretion and E-BP were closely associated (correlation for year 2: r = 0.734, P < 0.001), and also changes over the 2 years in E-UAE and E-BP were positively correlated (r = 0.53, P = 0.01). At year 2, overnight UAE, pre-exercise UAE (pre-E-UAE), E-UAE and E-BP were all closely linked (r-values between 0.6 and 0.9, P-values < 0.01). In the prediction of changes in overnight UAE over 2 years, neither baseline E-UAE nor baseline E-BP conveyed explanatory information in comparison with baseline overnight UAE and HbA1c.

CONCLUSIONS

In type 1 diabetic patients with low-grade microalbuminuria, 2 years of ACE-i treatment with lisinopril significantly reduced E-UAE. Strong correlations were found between E-UAE and E-BP and also changes over 2 years in these parameters were significantly associated.

Choice of time for urine collection for detecting early kidney abnormalities in hypertensives

The aim of this study was to determine the most appropriate urine collection for detecting differences in the excretion rates of albumin, gamma glutamyl transpeptidase (GGT) and N-acetyl-beta-D-glucosaminidase (NAGA) between normotensive subjects and hypertensive patients on treatment. Twenty treated hypertensive patients, mean (SEM, standard error of mean) age; 52.2 (6.2) years and 20 normotensive subjects, mean age 49.2 (4.2) years, were studied in a consecutive sampling design. Urinary excretion rates of albumin, GGT and NAGA were determined in consecutive timed urine samples collected overnight and during 3-5 h the next morning. Mean (SEM) overnight excretion rates for albumin, GGT and NAGA for normotensive subjects were 11.05 (1.18) micrograms/min, 17.00 (2.20) mU/min and 6.55 (0.39) mU/min, respectively, which were significantly lower than those of hypertensive subjects which were 20.77 (2.14) micrograms/min, 21.84 (1.65) mU/min and 10.92 (0.87) mU/min, respectively (P < 0.05). The mean (SEM) percentage increases in urinary albumin, GGT and NAGA in morning urine collections of normotensive subjects of 15.22 (3.88)%, 34.04 (6.45)% and 11.54 (3.63)%, respectively were significantly lower than 107.03 (15.04)%, 121.96 (16.71)% and 72.75 (7.50)% found in hypertensive patients (P < 0.05). These data suggest that were urinary albumin and tubular enzyme excretion to be used as correlates of hypertensive renal damage, ambulatory urine collections may be more sensitive than overnight collections.

Systemic blood pressure and glomerular leakage with particular reference to diabetes and hypertension

Both day and night blood pressure have considerable ranges in normal individuals and also in diabetic patients. In addition, there is considerable variation intra-individually, with considerable excurses in blood pressure, e.g. during exercise, other daily activities as well as on exposure to medical personnel. There is good evidence to suggest that elevated blood pressure is an important factor in the progression of renal disease in diabetes, even from the initial phase of the slight elevation of the albumin excretion rate. From the earliest phase of microalbuminuria, blood pressure may increase by an average of 3-4 mmHg per year in contrast to 1 mmHg per year in healthy controls and in clearly normoalbuminuric individuals. Throughout the course of the complications of diabetes, both insulin-dependent and non-insulin-dependent, there is a correlation between albuminuria and blood pressure in cross-sectional studies; also there is a significant correlation between blood pressure and the progression of albuminuria. The same findings are available in essential hypertension and also to some extent in the background population, although in the latter the correlation between albuminuria and blood pressure is much less precise, although highly significant. Several trials conducted over the years uniformly show that antihypertensive treatment reduces albuminuria and, in many studies, progression in renal disease also, as measured by the glomerular filtration rate (GFR) fall. Therefore, it could be considered as a means to reduce blood pressure generally in diabetic individuals, even from the start of diabetes, with the aim of future further prevention of renal complications and possibly other complications. Such a proposal is less attractive in the background population because renal disease is much more rare. Another similar approach would be the prevention of renal disease, e.g. diabetics. Obviously, abnormalities in the vascular wall of a biochemical/functional nature may make diabetics more pressure-sensitive, and the indication is that several other risk factors are involved, in particular poor metabolic control. Nevertheless, it is proposed that trials should be conducted very early in the course of diabetes, to see if the same positive effect can be obtained early as that documented later in the course of microalbuminaria and overt renal disease, both in insulin-dependent and in non-insulin-dependent diabetes. In essential hypertension, antihypertensive treatment has a profound effect on albuminuria, and this may be associated with long-term renoprotection, but this is less well documented.

Exercise electrocardiography and aortic Doppler velocimetry in asymptomatic identical twins discordant for type 1 (insulin dependent) diabetes

OBJECTIVE

To determine the influence of insulin dependent diabetes on the prevalence of myocardial ischaemia and on global left ventricular systolic performance.

DESIGN

Stress treadmill electrocardiograms and simultaneous Doppler measurement of aortic maximum acceleration were obtained during exercise on symptom free subjects. The electrocardiograms were scored blindly according to the Minnesota code.

PARTICIPANTS

39 identical twin pairs (22 male) discordant for insulin dependent diabetes and 39 non-diabetic controls of similar age and sex were examined. The twins and controls had a mean age of 37 (range 25-69) with a mean (SD) duration of diabetes in the diabetic twin of 17 (7) years. Those selected were normotensive and had no renal impairment.

RESULTS

Systolic blood pressure was significantly higher in the diabetic twins than in their non-diabetic cotwins both at rest (p < 0.05) and at peak exercise (p < 0.01). Electrocardiographic evidence of ischaemia was not correlated within twin pairs and was found in similar numbers of diabetic twins, their non-diabetic cotwins, and control subjects. Abnormal electrocardiograms were found in a similar number of diabetic twins (23%), non-diabetic cotwins (18%), and controls (15%). There was a significant correlation in Doppler measurements of global left ventricular systolic function within the identical twins; no significant difference was found for these Doppler measurements in the diabetic twins, non-diabetic cotwins, or controls.

CONCLUSION

Exercise characteristics and cardiac function seem to be subject to shared genetic or shared environmental influences or both, whereas electrocardiographic features of ischaemia seem to be environmentally determined. In a selected cohort of diabetic identical twins without evidence of nephropathy there was no evidence that diabetes influenced the prevalence of myocardial ischaemia or global left ventricular systolic function.

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

We examined two groups of non-insulin-dependent diabetic men (group A, 13 patients without microalbuminuria; group B, 9 patients with intermittent microalbuminuria) to ascertain whether the anaerobic threshold (AT) can provoke microalbuminuria, comparing them with 12 healthy subjects matched for age and sex (group C). All subjects exercised on a bicycle ergometer until the AT was reached. In intermittent microalbuminuria, the albumin:creatinine ratio (ACR) was over 0.25 mg/mmol.Cr 1-3-fold in 5 measurements. The ACR after exercise was increased to over 0.25 mg/mmol.Cr in 4/9 cases in group B (P < 0.05), in 2/13 cases in group A, but not at all in group C. We also studied the mechanism of exercise-induced microalbuminuria. In group B, ACR before exercise correlated positively with the baseline plasma glucose. Furthermore, positive correlation was found between ACR after exercise and HbA1c in group B. The AT did not affect the urinary beta 2-microglobulin in any groups. The plasma atrial natriuretic factor (ANF) after exercise was elevated most prominently in group B (P < 0.05). Positive correlation was found between increments of ACR and increments of plasma ANF after exercise in group B. We conclude that the AT can provoke microalbuminuria in some non-insulin-dependent diabetics. The plasma ANF and metabolic control may play an important role in the pathophysiology of exercise-induced microalbuminuria.

Involvement of the renin angiotensin system in the pathogenesis of postexercise proteinuria

Proteinuria after strenuous exercise is common in healthy subjects. The pathophysiologic mechanism of postexercise proteinuria (PEP) is not clear, although the phenomenon has long been known and many explanatory theories have been proposed. It is widely recognized that angiotensin II may increase filtration of protein through the glomerular membrane, and that its concentration in plasma increases during exercise. The aim of this study was to evaluate possible involvement of angiotensin II in the pathogenesis of PEP. Of 25 young volunteers who performed maximal aerobic exercise, eight showed PEP. The exercise was repeated after an interval of at least one week, now 90 minutes after administration of captopril (25 mg). Captopril did not affect the achieved work load of the maximal blood pressure and heart rate during the exercise, but PEP was not found. As it was possible to prevent PEP by administering an angiotensin-converting enzyme inhibitor, the study supports the theory that the renin angiotensin system is involved in the pathogenesis of PEP.

Microalbuminuria is a marker of left ventricular hypertrophy but not hyperinsulinemia in nondiabetic atherosclerotic patients

Microalbuminuria predicts cardiovascular events in diabetic and nondiabetic patients. For a better understanding of the physiopathological importance of microalbuminuria in atherosclerotic disease, we evaluated the relation between urinary albumin excretion and arterial blood pressure, left ventricular mass, insulin, and lipid levels. The studies were conducted in patients with atherosclerotic peripheral vascular disease. Urinary albumin excretion (studied by nephelometry; an average of triplicate collections from 8 PM to 8 AM), causal blood pressure, echocardiographic left ventricular mass index and wall thickness, plasma immunoreactive insulin and C-peptide (both basally and after a 75-g oral glucose load), blood lipids, and fibrinogen were studied in eight normal subjects and 20 nonobese, nondiabetic male patients with angiographically documented atherosclerotic peripheral vascular disease and preserved renal function, 12 of whom were either hypertensive or on antihypertensive treatment. Eight patients were microalbuminuric (urinary albumin > 20 micrograms/min) and 12 were not. Ankle-arm index and calf and foot transcutaneous oxygen tension were reduced in comparison with normal control subjects but superimposable between the two patient groups to indicate a comparable clinical progression of the vascular disease. In the microalbuminuric subjects, left ventricular mass index was greater, interventricular septum was thicker, and cardiac hypertrophy was more frequent than in nonmicroalbuminuric patients. The prevalence of hypertension tended to be greater and systolic blood pressure values were higher in the presence of microalbuminuria. Overall, a highly significant relation existed between urinary albumin excretion and left ventricular mass. Systolic blood pressure was greater and a history of arterial hypertension was more frequent among microalbuminurics, whereas diastolic blood pressure values showed a statistically significant correlation with both variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Isradipine decreases exercise-induced albuminuria in patients with essential hypertension

The aim of our study was to investigate the effects of exercise on albuminuria and blood pressure in patients with essential hypertension, and the short-term effect of the calcium channel blocker isradipine on exercise-induced albuminuria (UAE) and blood pressure in the same patients. Ten patients (7 males, 3 females) with essential hypertension were admitted to the study. The mean age was 54 +/- 2.7 years and the mean body mass index was 27 +/- 1 kg/m2. Patients performed two physical exercise tests on a cycloergometer. Workload was increased by 30 watts every 2 min until 90% of the theoretical maximal heart rate was achieved. This workload was maintained for 5 min. Samples for albuminuria assay were collected at the end of exercise and 1 h after exercise. The first physical exercise test was performed after 15 days of placebo washout; the second exercise was performed after 10 days of therapy with isradipine 5 mg once daily p.o. After 10 days of therapy with isradipine, UAE immediately after (31 +/- 8.3 micrograms/min) and 1 h after exercise (31.5 +/- 7.3 micrograms/min) were significantly (p < 0.05) lower as compared to the values found after placebo (37.1 +/- 9.3 micrograms/min; 43.5 +/- 9.9 micrograms/min). Our data show that short-term administration of the calcium channel blocker isradipine is able to cause a concomitant significant decrease in exercise-induced pressor and albuminuric response in patients with essential hypertension. The finding that short-term calcium channel blockade can reduce exercise-induced albuminuria in essential hypertensive patients suggests that progression of nephropathy in this early phase could be slowed by isradipine in these patients.

Abnormal plasma noradrenaline response and exercise induced albuminuria in type 1 (insulin-dependent) diabetes mellitus

Submaximal exercise provokes an abnormal elevation in albuminuria in type 1 (insulin-dependent) diabetes mellitus. Plasma catecholamines might be involved in this phenomenon by a renal vasoconstrictive effect. Twelve healthy subjects (Controls: albuminuria < 10 micrograms min-1), 13 normoalbuminuric type 1 diabetic patients (DNormo: albuminuria < 10 micrograms min-1) and 13 microalbuminuric type 1 diabetic patients (DMicro: albuminuria 10-200 micrograms min-1) performed a fixed bicycle workload (600 kpm for 20 min+urine collection 40 min post exercise). None of the patients suffered from autonomic neuropathy or hypertension. Fractional albumin clearance (FalbCl) rose in DNormo (p = 0.02) and DMicro (p = 0.01) but not in the Controls (p = 0.40). Basal plasma adrenaline and noradrenaline were not different in the three groups. The increments in noradrenaline were more pronounced in DNormo and DMicro than in Control (Controls < DNormo, p < 0.05; Controls < DMicro, p < 0.01). The changes in FalbCl were significantly correlated with the changes in noradrenaline (all subjects r = 0.65, p < 0.001). The increments in adrenaline were not different in the diabetic groups compared to the controls, and were not related to the changes in FalbCl. Multiple regression analysis showed that changes in plasma noradrenaline (p < 0.002) and in mean arterial pressure (p < 0.005) independently contributed to the changes in FalbCl (multiple r = 0.73). It is concluded that the exercise-induced plasma noradrenaline response is increased in normo- and microalbuminuric type-1 diabetic patients. Noradrenaline appears to contribute in the exercise-induced changes in renal protein handling, possibly by its effect on renal haemodynamics.

Diabetes mellitus and hypertension

Diabetes mellitus and hypertension are common diseases that coexist at a greater frequency than chance alone would predict. Hypertension in the diabetic individual markedly increases the risk and accelerates the course of cardiac disease, peripheral vascular disease, stroke, retinopathy, and nephropathy. Our understanding of the factors that markedly increase the frequency of hypertension in the diabetic individual remains incomplete. Diabetic nephropathy is an important factor involved in the development of hypertension in diabetics, particularly type I patients. However, the etiology of hypertension in the majority of diabetic patients cannot be explained by underlying renal disease and remains "essential" in nature. The hallmark of hypertension in type I and type II diabetics appears to be increased peripheral vascular resistance. Increased exchangeable sodium may also play a role in the pathogenesis of blood pressure in diabetics. There is increasing evidence that insulin resistance/hyperinsulinemia may play a key role in the pathogenesis of hypertension in both subtle and overt abnormalities of carbohydrate metabolism. Population studies suggest that elevated insulin levels, which often occurs in type II diabetes mellitus, is an independent risk factor for cardiovascular disease. Other cardiovascular risk factors in diabetic individuals include abnormalities of lipid metabolism, platelet function, and clotting factors. The goal of antihypertensive therapy in the patient with coexistent diabetes is to reduce the inordinate cardiovascular risk as well as lowering blood pressure.

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

Microalbuminuria is thought to be an important prognostic factor in diabetes mellitus. To study the influence of changes in blood pressure on the development of microalbuminuria during exercise, two exercise tests were carried out. A total of 32 insulin dependent diabetic men whose age at onset was less than 30 years, mean duration of diabetes 14 years (range 7 to 21) and mean age 29 years (range 21 to 40), and who did not have albuminuria (N-labstix negative) were studied. The diabetic patients were compared with a total of 29 age-matched male control subjects. Urinary albumin excretion was measured during two exercise tests: at a standardised workload (150 W) for 30 min, and at a standardised heart rate for 25 min. The diabetic patients had higher albumin excretion rates during both exercise tests compared with the control subjects. Blood pressure and heart rate during exercise were significantly higher in diabetic patients compared with control subjects in the standardised workload test. If the test was individualised to achieve the same standardised heart rate there was no significant difference in blood pressure between the diabetic patients and the control subjects. These results indicate that the diabetic kidneys were more sensitive than the healthy kidneys to similar degrees of haemodynamic stress induced by exercise.

Catecholamines and blood glucose control in type 1 diabetes

To evaluate the influence of blood glucose control on serum catecholamine levels (which reflect both plasma and platelet levels), six healthy non-diabetic subjects, seven well-controlled Type 1 diabetic patients, and six poorly controlled Type 1 diabetic patients were studied before (baseline) and after standardized exercise. A significant correlation was found between serum noradrenaline and HbA1 at baseline (r = 0.53, p less than 0.025) and after exercise (r = 0.71, p less than 0.001). Similar results were found for serum adrenaline (r = 0.68, p less than 0.005 and r = 0.61, p less than 0.005, respectively) and consequently total serum catecholamine content (r = 0.65, p less than 0.005 and r = 0.75, p less than 0.001, respectively). However, no relationship was found between serum catecholamine levels and actual blood glucose levels, age, body mass index or insulin dose. A moderate correlation was found between systolic blood pressure and serum levels of noradrenaline and total catecholamines after exercise (r = 0.48 and r = 0.48, both p less than 0.025).

An acceptable exercise test to study microalbuminuria in type 1 diabetes

A modified test for studying the response of urinary albumin excretion (UAV) to exercise in diabetic patients is described. It is designed to produce a standardized increase in pulse rate (by 90-110%) rather than a standardized workload. Thirty-three normotensive Type 1 diabetic patients with normal pre-exercise UAV (less than 10 micrograms min-1) on the day of the test were compared with 25 non-diabetic subjects matched for age and sex. The patients developed a significantly greater increase in the median UAV (p less than 0.05) and systolic blood pressure (p less than 0.01) during exercise, despite the use of lower workloads (p less than 0.05). During exercise, the albumin excretion in the patients was not related to their heart rate, blood pressure, workload or fall in blood glucose; nor was it related to duration of diabetes, glycosylated haemoglobin or insulin dose. An exercise UAV greater than 15 micrograms min-1 was found in 10 of the 33 patients; it was significantly correlated (p less than 0.01) with the frequency of previous overnight microalbuminuria (greater than 10 micrograms min-1), and was associated with a greater progression of microalbuminuria (p less than 0.05) over a mean period of 24 months. Retinol-binding protein excretion rate was also measured as an indicator of proximal tubular function and did not increase in either group.

Early renal involvement and nephropathy. Can treatment modalities be predicted from identification of risk factors in diabetics?

There is now circumstantial evidence indicating that initiation and progression of renal disease in diabetes is associated with the degree of metabolic control, although modifying factors, such as elevation of blood pressure and, possibly, dietary protein intake, are important. Further, there is differential susceptibility, and more studies are clearly needed to clarify why some patients develop nephropathy and others do not, despite similar metabolic control. Metabolic control, blood pressure level and protein intake are probably not only risk factors but are also involved in the pathogenesis of diabetic nephropathy. Thus, intervention by optimizing glycaemic control and blood pressure treatment and by low-protein diets appears possible and can be recommended as a prudent treatment programme. Early clinical detection of patients at risk for late nephropathy is already possible, since easy, rapid, inexpensive methods for detecting microalbuminuria are now available.

The diabetic kidney: from hyperfiltration and microalbuminuria to end-stage renal failure

This article describes many new concepts within the area of diabetic renal involvement and diabetic renal disease. Considerable progress has taken place within this area, not only regarding diagnosis of early diabetic nephropathy but also the early treatment of nephropathy in its incipient stage.

Effect of the exercise test on albuminuria, blood pressure and blood glucose in type I (insulin-dependent) diabetic patients

Twenty-nine male type I diabetic patients (age range 16-46 years) and thirteen healthy men (age range 18-43 years) were exercised on a cycling ergometer at 75 W and 100 W after having achieved a steady state of water diuresis. Diabetic patients were subdivided into Group A (n = 19, resting urinary albumin excretion rate - UAER less than or equal to 16 micrograms/min) and Group B (n = 10, 16 less than resting UAER less than 126 micrograms/min). The groups were comparable in weight, serum creatinine, duration of diabetes and glycosylated hemoglobin. Group B showed the highest elevation of UAER at the work load of 100 W, with no correlation between increase in UAER and increase in systolic blood pressure (SBP) at both work loads. The only correlation between these parameters was found in Group A at the work load of 100 W (p less than 0.05). No correlation was found between exercise UAER and actual blood glucose in either group. The difference in UAER between healthy subjects and Group B patients (p less than 0.001) remained on the same level during exercise as at rest, but the difference between Group A and Group B (p less than 0.001) decreased with increasing work load (p less than 0.05). The highest exercise-induced systolic and diastolic blood pressure (DBP) was found in Group B, although there was no difference between the diabetic groups in pre-exercise blood pressure and in mean SBP and DBP from previous outpatient check-ups. Blood glucose did not change significantly during exercise in either diabetic group. Working capacity of diabetic patients was lower than that of healthy subjects. The test revealed some diabetic patients with strong elevation of UAER and with abnormally raised systolic and diastolic BP during exercise. The value of the findings reported is to be clarified in a further longitudinal study.

Comparison of overnight, morning and 24-hour urine collections in the assessment of diabetic microalbuminuria

With the aim of comparing different urine collection periods in the assessment of micro-albuminuria, urinary albumin excretion rates (AERs) were measured in samples from 24 h, overnight, and morning urine collections in 54 patients aged 17 to 62 years with insulin-dependent diabetes mellitus with a mean duration of 15 years. The AER in overnight urine was found to be reduced by 25% compared to the rate in 24 h and morning urine. Assessing the ability to predict a 24 h AER within the microalbuminuric range (20-200 micrograms/min) we found a sensitivity of 90% and a specificity of 88% for both overnight and morning urine samples. These values were slightly improved by relating AER to the excretion of creatinine and it is concluded that overnight as well as morning urine collections can be used when diagnosing microalbuminuria in insulin-dependent diabetics. Furthermore the results show that the albumin to creatinine ratio in morning urine is a reliable estimate of 24 h AER and better than measurement of the albumin concentration alone.

Converting enzyme inhibition and kidney function in normotensive diabetic patients with persistent microalbuminuria

The effects of a long term reduction in blood pressure on the kidney function of normotensive diabetic patients who had persistent microalbuminuria (30-300 mg albumin/24 hours) were studied in two groups of 10 such patients before and during six months of treatment with either 20 mg enalapril or placebo daily. Treatments were assigned randomly in a double blind fashion. Before treatment both groups had similar clinical characteristics, weight, diet, total glycosylated haemoglobin, median albumin excretion rate (enalapril group 124 mg/24 h, placebo group 81 mg/24 h), and mean arterial pressure (enalapril group 100 (SD 8) mm Hg, placebo group 99 (6) mm Hg). During treatment weight, urinary urea excretion, and total glycosylated haemoglobin remained unchanged. The mean arterial pressure decreased in the enalapril group but not in the placebo group (enalapril group 90 (10) mm Hg, placebo group 98 (8) mm Hg). The median albumin excretion rate also fell in the enalapril group but not in the placebo group (enalapril group 37 mg/24 h, placebo group 183 mg/24 h.) The glomerular filtration rate rose in the enalapril group from 130 (23) ml/min/1.73 m2 to 141 (24) ml/min/1.73 m2, and total renal resistances and fractional albumin clearance decreased while fractional albumin clearance increased in the placebo group. These results show that in patients who have diabetes but not hypertension a reduction in blood pressure by inhibition of converting enzyme for six months can reduce persistent microalbuminuria, perhaps by decreasing the intraglomerular pressure.

A solid phase enzyme immunoassay for the measurement of urinary albumin and the detection of microalbuminuria

A test for the measurement of trace urinary albumin concentrations, which is suitable for the detection of microalbuminuria, was developed. The technique is an indirect enzyme-linked assay (ELISA) in which a fixed amount of anti-albumin antibody is placed into polystyrene tubes coated with human albumin, together with the urine sample to be tested. The albumin in the test specimen competes with the solid-phase albumin for binding to the added antibody. The test is precise (inter- and intra-assay coefficients of variation were 8.2% and 7.8%, respectively), accurate (mean recovery 102-106% for two human albumin preparations), and sensitive (detection limit 0.9 micrograms/ml). These characteristics are not dissimilar from those of the radioimmunoassay reported in the literature, with the advantages of being completely safe, easy to perform, and not requiring expensive equipment. Using this assay the urinary albumin excretion in 20 normal subjects was found to be 2.5 +/- 2.2 micrograms/min (range 0.9-7.5 micrograms/min) after 8 hours of bed rest and 4.5 +/- 5.7 micrograms/min (range 1.5-2.0 micrograms/min) after 8 hours of moderate physical activity.

Antihypertensive treatment: long-term reversal of progression of albuminuria in incipient diabetic nephropathy. A longitudinal study of renal function

This study was undertaken to clarify whether antihypertensive treatment has any effect on the rate of progression of kidney disease in patients with incipient diabetic nephropathy. Six insulin-dependent diabetic men with incipient nephropathy (urinary albumin excretion above 15 micrograms/min and total protein excretion below 0.5 g/24 h) were first given metoprolol (200 mg daily) with the subsequent addition of hydroflumethiazide. At the start of antihypertensive treatment, mean patient age was 32 +/- 4.2 years (SD) and mean duration of diabetes was 18 +/- 1.2 years. The patients were followed with repeated measurements of urinary albumin excretion for a mean of 5.4 +/- 3.1 years prior to, and for 4.7 +/- 1.3 years (SD) during treatment. Mean arterial blood pressure declined significantly during treatment, e.g., the values at 6 months before initiation of treatment being compared with values during the last 6 months of treatment fell from 107 mmHg +/- 7.6 to 93 +/- 3.8 (2p = 1.5%). Albumin excretion decreased from 131.0 micrograms/min X/divided by 2.9 (geometric mean X/divided by tolerance factor) to 41.7 micrograms/min X/divided by 2.9 (2p = 1.2%). Albumin clearance in per cent of glomerular filtration rate decreased from a mean of 0.0030 +/- 0.0019% (SD) to 0.0011 +/- 0.0010% (2p = 4.6%). The mean yearly increase in urinary albumin excretion before treatment was 18.0 +/- 17.0% (mean +/- SD); during treatment urinary albumin excretion decreased 19 +/- 10% per year (2p = 0.7%). No changes were seen in renal plasma flow (516 +/- 31.0 ml/min to 520 +/- 66 ml/min (n = 5)).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute and long-term effect of antihypertensive treatment on exercise-induced albuminuria in incipient diabetic nephropathy

The aim of the study was to clarify whether antihypertensive treatment could affect the systolic blood pressure (SBP) and urinary albumin excretion (UAE) in diabetics during exercise (450 kpm/min, followed by 600 kpm/min, 20 min each). Young male insulin-dependent diabetics with normal UAE (n = 9) and diabetics with incipient nephropathy (n = 7) were examined in an acute study. Five patients with incipient diabetic nephropathy participated in a long-term study. Incipient diabetic nephropathy is defined as persistently elevated UAE (greater than 15 micrograms/min), but no clinical proteinuria. In the acute study, using placebo/metoprolol 10 mg i.v. in patients with normal UAE, the maximal SBP at 600 kpm/min was reduced by 17 mmHg +/- 10 (SD) (2p less than 1.0%) and the maximal SBP at 600 kpm/min in the patients with incipient nephropathy was reduced by 15 mmHg +/- 11 (SD) (2p less than 1.0%). However, no difference was observed in UAE, in patients with normal UAE or those with incipient nephropathy. Five of the patients with incipient nephropathy were followed with repeated exercise tests before and during 2.6 years of antihypertensive treatment, using metoprolol 200 mg/24 h and subsequently also hydroflumethiazid 25 mg/24 h. The maximal SBP at 600 kpm/min at the end of the study compared to the pretreatment level was reduced by 38 mmHg +/- 12 (SD) (2p less than 1.0%), and furthermore the exercise-induced elevated UAE was reduced by 61% +/- 29 (SD) (2p = 2.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Early glomerular hyperfiltration in insulin-dependent diabetics and late nephropathy

The aim of this study was to clarify whether early glomerular hyperfiltration, a characteristic feature of insulin-dependent diabetes, is associated with late diabetic nephropathy. In 1984 we re-examined 12 patients previously investigated in our laboratory around 1970; entrance criteria were as follows: male diabetics, clearly insulin-dependent, and age at onset of diabetes less than or equal to 20 years; glomerular filtration rate (GFR) and renal plasma flow (RPF) measured at least 7 years before follow-up study; duration of diabetes at initial examination 3-7 years. All patients fulfilling these criteria accepted a re-examination. The end-point at follow-up (final criterium) was the level of urinary albumin excretion (UAE), either elevated (greater than or equal to 15 micrograms/min) or normal (less than 15 micrograms/min). A clear discrimination was seen, patients being either grossly abnormal (95-4117 micrograms/min) or normal (2.6-7.4 micrograms/min). A marked difference in initial GFR was seen: 166 ml/min +/- 15.4 in those with high UAE at follow-up versus 138 +/- 8.6 in patients with normal UAE at follow-up (2p = 0.2%). The GFR at follow-up was significantly decreased in diabetics with high follow-up UAE (mean values 166----80 ml/min) but stable in patients with low UAE (138----132 ml/min). Initial blood pressure, plasma glucose and RPF were not different between groups. Marked glomerular hyperfiltration, whatever its cause, may contribute to late glomerular damage in diabetic nephropathy. Early measurements of GFR and UAE can be used to identify patients at risk of subsequently developing nephropathy.

Acute reduction of arterial blood pressure reduces urinary albumin excretion in type 1 (insulin-dependent) diabetic patients with incipient nephropathy

The effect of an acute reduction in arterial blood pressure upon kidney function was studied in 12 patients with Type 1 (insulin-dependent) diabetes and incipient nephropathy (persistent microalbuminuria). Renal function was assessed by measurement of the glomerular filtration rate (single bolus 51Cr-EDTA technique) and by the urinary albumin excretion rate (radioimmunoassay). The study was performed twice within 2 weeks, with the patients receiving a slow intravenous injection of either clonidine (225 micrograms) or saline (154 mmol/l) in random order. Clonidine reduced arterial blood pressure from 125/79 +/- 13/8 to 104/68 +/- 9/7 mmHg (p less than 0.01), urinary albumin excretion rate from 68 (31-369) to 46 (6-200) micrograms/min (median and range) (p less than 0.01), and fractional clearance of albumin in all patients (median 29%) (p less than 0.01). Glomerular filtration rate was 110 +/- 11 before and 106 +/- 13 ml/min/1.73 m2 after clonidine injection. The blood glucose concentration was 15 +/- 4 mmol/l before and 14 +/- 5 mmol/l after clonidine injection. In agreement with findings in animal studies, our results suggest that microalbuminuria is to a large extent pressure-dependent, probably because of glomerular hypertension, and that autoregulation of glomerular filtration rate is normal in most patients with incipient diabetic nephropathy.

Kidney function during 12 months of strict metabolic control in insulin-dependent diabetic patients with incipient nephropathy

Thirty-six patients with insulin-dependent diabetes mellitus who had Albustix-negative urine but elevated urinary albumin excretion (30 to 300 mg per 24 hours) were matched in pairs according to their urinary albumin level, blood glycosylated hemoglobin level, and sex and assigned randomly to either unchanged conventional treatment or continuous insulin infusion. During the next 12 months a significant improvement in glycemic control was observed in the insulin-infusion group, with a reduction in the mean glycosylated hemoglobin level from 9.5 to 7.3 percent. There was no change in the control group (9.3 to 9.2 percent). No significant change in albumin excretion was observed in either group. The mean blood pressure increased slightly in both groups (from 98 to 101 mm Hg in the insulin-infusion group and from 98 to 103 mm Hg in the control group). Kidney size was significantly reduced in all patients during insulin infusion, but no consistent change was observed in the control group. No significant change was observed in the glomerular filtration rate. Our data suggest that the pathologic processes causing microalbuminuria in early renal disease are not reversed during 12 months of strict metabolic control.

Effect of antihypertensive treatment on progression of incipient diabetic nephropathy

The aim of the study was to clarify whether antihypertensive treatment with a selective beta blocker would have an effect on the progression rate of kidney disease in patients with incipient diabetic nephropathy. Six male patients with juvenile-onset diabetes with incipient nephropathy (urinary albumin excretion above 15 micrograms/min and total protein excretion below 0.5 g/24 hr) were treated with metoprolol (200 mg daily). At the start of the antihypertensive treatment the mean age was 32 years +/- 4.2 (SD). The patients were followed a mean 5.4 years +/- 3.1 (SD) with repeated measurements of urinary albumin excretion before and during 2.6 years +/- 1.0 (SD) of treatment. The blood pressure was depressed by the treatment (systolic blood pressure from 135 mm Hg +/- 8.6 to 124 mm Hg +/- 6.2, NS; mean blood pressure from 107 mm Hg +/- 7.6 to 97 mm Hg +/- 3.4, 2p less than 0.05; diastolic blood pressure from 93 mm Hg +/- 9.1 to 84 mm Hg +/- 3.6, 2p less than 0.05. Albumin excretion decreased (131.0 micrograms/min X/divided by 2.9 [geometric mean X/divided by tolerance factor] to 56.1 micrograms/min X/divided by 3.7, 2p less than 0.02). The mean yearly increase in urinary albumin excretion before treatment was 18 +/- 17 (mean +/- SD). Albumin excretion decreased during treatment: 17% +/- 15 per year (mean +/- SD, 2p less than 0.02). No changes were seen in glomerular filtration rate or renal plasma flow (149 ml/min +/- 5.8 vs 144 ml/min +/- 11.1, and 516 ml/min +/- 31.0 vs 541 ml/min +/- 68.5 respectively [n = 5]).(ABSTRACT TRUNCATED AT 250 WORDS)

Enzyme immunoassay: an improved determination of urinary albumin in diabetics with incipient nephropathy

An enzyme linked immunoadsorbent assay for urinary albumin using commercially available reagents is described. The assay range is 2.5-120 micrograms/l. When samples are analysed in two standard dilutions, the assayable albumin concentration range is 2.5-240 mg/l, covering the clinical range from normoalbuminuria to overt clinical nephropathy. Intra-assay variation was 2.1% and interassay variation 8.3%. Recovery of added albumin to urine was 95%-106% and dilution of urine was linear. The correlation to urinary albumin determined by immunodiffusion was excellent (n = 80, r = 0.99). Intraindividual variation of the 24 h urine albumin excretion of different days was high in patients with incipient diabetic nephropathy (51.5%) and was only slightly reduced by taking the variation of creatinine excretion into account (39.5%). No correlation was found between albumin excretion, and HbA1c or urine glucose excretion, indicating that minor metabolic variations are not responsible for the huge intraindividual day-to-day variations of UalbV. The study shows that more than one UalbV measurement must be done before classifying patients into groups with or without incipient diabetic nephropathy.

Exercise as a provocative test in early renal disease in type 1 (insulin-dependent) diabetes: albuminuric, systemic and renal haemodynamic responses

The value of exercise as a provocative test for early renal disease in Type 1 (insulin-dependent) diabetes was re-evaluated. Three carefully characterized groups of males were studied: 10 non-diabetic controls, 16 diabetic patients (group 1) with normal urinary albumin excretion (less than 15 micrograms/min) and 14 Albustix-negative diabetics (group 2) with increased urinary albumin excretion (15-122 micrograms/min). Assignment to a study group was made on the basis of three 24-h urine collections, and the groups were well matched for age, weight, height, and serum creatinine concentration. The two diabetic groups were similar with regard to duration of disease (13 +/- 6 versus 16 +/- 3 years), metabolic control (HbA1c: 8.4 +/- 1.4 versus 8.7 +/- 1.3%) and degree of diabetic complications (beat-to-beat variation and retinopathy). An exercise protocol of 450 and 600 kpm/min workloads was employed. In the resting state group 2 patients had elevated systolic blood pressure compared with the normal subjects (132 +/- 13 versus 119 +/- 9 mmHg), and their glomerular filtration rate was significantly reduced compared with group 1 (123 +/- 19 versus 138 +/- 15 ml/min per 1.73 m2, p less than 0.05). During exercise the urinary albumin excretion rate increased significantly in all three groups (normal subjects: 6 +/- 0.7 to 8 +/- 1.3 (microgram/min); group 1: 6 +/- 0.6 to 9 +/- 1 microgram/min and group 2: 48 +/- 10 to 113 +/- 23 micrograms/min), the relative increase being higher in group 2 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)