Graded exercise and protein excretion in diabetic man and the effect of insulin treatment

An Open-label Comparison of a New Generic Sevoflurane Formulation With Original Sevoflurane in Patients Scheduled for Elective Surgery Under General Anesthesia

PURPOSE

To compare the stability, effectiveness, and safety profiles of a new generic sevoflurane with those of the original sevoflurane formulation in patients undergoing elective surgery.

METHODS

An accelerated 3-month storage test was performed to evaluate the compositional changes in generic sevoflurane stored in glass bottles. In addition, 182 patients were randomly allocated to receive generic (n = 89 [54 men and 35 women]; mean [SD] age, 49.9 [11.6] years) or original (n = 93 [61 men and 32 women]; mean [SD] age, 49.6 [11.1] years) sevoflurane at a gas flow of 3 L/min for approximately 3 hours. The mean minimum alveolar concentration (MAC) during sevoflurane anesthesia was evaluated, and gas samples for measuring compound A were collected from the inspiratory limb of the circuit at preset intervals. Blood samples for measuring serum inorganic fluoride were obtained at preset intervals (pharmacokinetic group: generic/original sevoflurane = 45/46). Renal biomarkers, such as N-acetyl-β-glucosaminidase, α- and π-glutathione-S-transferase, albumin, urine protein and osmolality, serum creatinine and osmolality, creatinine clearance, and blood urea nitrogen, were measured at preset intervals (renal biomarker group: generic/original sevoflurane = 44/47). Adverse reactions were monitored for 72 hours after discontinuation of sevoflurane use.

FINDINGS

Generic sevoflurane contained in glass bottles was stable for 3 months. The mean MAC was similar for generic and original sevoflurane (median [range], 0.93 [0.67-1.29] vs 0.94 [0.63-1.5] vol%). Adverse event rates were similar (90.3% vs 84.3%), as were the AUClast of inorganic fluoride (333.7 [112.7-1264.7] vs 311.9 [81.5-1266.5] hours·μmol/L) and compound A (51.8 [6.3-204.5] vs 55.3 [10.8-270.6] hours·ppm). Biomarkers associated with renal injury were not significantly different between the 2 formulations.

IMPLICATIONS

No significant difference was found in the mean MAC between generic and original sevoflurane. ClinicalTrials.gov identifier: NCT01096212.

Effect of exercise intensity on albuminuria in adolescents with Type 1 diabetes mellitus

AIMS

Exercise may be useful to detect patients with diabetes prone to develop persistent microalbuminuria. We studied the relationship between exercise intensity, measured as maximal oxygen consumption (VO(2)max), and microalbuminuria in patients with Type 1 diabetes mellitus patients.

METHODS

We studied 10 patients, age range 10-18 years, with Type 1 diabetes who were normotensive and normoalbuminuric, with less than 10 years since diagnosis. Patients had normal renal function, without infections or clinical evidence of complications. Metabolic control was intensively adjusted in all patients. They underwent three consecutive physical exercise tests, reaching 100, 80 and 60% of the maximal cardiac frequency response.

RESULTS

Eight patients had adequate to regular metabolic control. All patients had lower than predicted VO(2)max values. At 60%, only three patients showed microalbuminuria in excess of 20 μg/min, two of them had inadequate metabolic control. Post-exercise microalbuminuria exceeded normal values in nine, seven and three patients when submitted to 100, 80 and 60% of exercise intensity, respectively.

CONCLUSIONS

Microalbuminuria increased with exercise intensity. Sex, body composition and VO(2)max were the main factors associated with microalbuminuria. The prognostic significance of albuminuria induced by intense exercise in these subjects with Type 1 diabetes is not yet known.

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.

Current issues in measurement and reporting of urinary albumin excretion

BACKGROUND

Urinary excretion of albumin indicates kidney damage and is recognized as a risk factor for progression of kidney disease and cardiovascular disease. The role of urinary albumin measurements has focused attention on the clinical need for accurate and clearly reported results. The National Kidney Disease Education Program and the IFCC convened a conference to assess the current state of preanalytical, analytical, and postanalytical issues affecting urine albumin measurements and to identify areas needing improvement.

CONTENT

The chemistry of albumin in urine is incompletely understood. Current guidelines recommend the use of the albumin/creatinine ratio (ACR) as a surrogate for the error-prone collection of timed urine samples. Although ACR results are affected by patient preparation and time of day of sample collection, neither is standardized. Considerable intermethod differences have been reported for both albumin and creatinine measurement, but trueness is unknown because there are no reference measurement procedures for albumin and no reference materials for either analyte in urine. The recommended reference intervals for the ACR do not take into account the large intergroup differences in creatinine excretion (e.g., related to differences in age, sex, and ethnicity) nor the continuous increase in risk related to albumin excretion.

DISCUSSION

Clinical needs have been identified for standardization of (a) urine collection methods, (b) urine albumin and creatinine measurements based on a complete reference system, (c) reporting of test results, and (d) reference intervals for the ACR.

Microalbuminuria and urinary albumin excretion: French clinical practice guidelines

Urinary albumin excretion (UAE) may be assayed on a morning urinary sample or a 24 h-urine sample. Values defining microalbuminuria are: 1) 24-h urine sample: 30-300 mg/24 h; 2) morning urine sample: 20-200 mg/ml or 30-300 mg/g creatinine or 2.5-25 mg/mmol creatinine (men) or 3.5-35 mg/mmol (women); 3) timed urine sample: 20-200 mug/min. The optimal use of semi-quantitative urine test-strip is not clearly defined. It is generally believed that microalbuminuria reflects a generalized impairment of the endothelium; however, no definite proof has been obtained in humans.

IN DIABETIC SUBJECTS

Microalbuminuria is a marker of increased risk of cardiovascular (CV) and renal morbidity and mortality in type 1 and type 2 diabetic subjects. The increase in UAE during follow-up is associated with greater CV and renal risks in type 1 and type 2 diabetic subjects; its decrease during follow-up is associated with lower risks. IN NON-DIABETIC SUBJECTS: Microalbuminuria is a marker of increased risk for diabetes mellitus, deterioration of renal function, CV morbidity and all-cause mortality. It is a marker of increased risk for the development of hypertension in normotensive subjects, and is associated with unfavorable outcome in patients with cancer and lymphoma. Persistence of elevated UAE during follow-up is associated with poor outcome in some hypertensive subjects. Measurement of UAE may be recommended in hypertensive medium-risk subjects with 1 or 2 CV risk factors in whom CV risk remains difficult to assess, and in those with refractory hypertension: microalbuminuria indicates a high CV risk and must lead to strict control of arterial pressure. Studies focused on microalbuminuria in non-diabetic non-hypertensive subjects are limited; most of them suggest that microalbuminuria predicts CV complications and deleterious outcome. Subjects with a history of CV or cerebrovascular disease have an even greater CV risk if microalbuminuria is present than if it is not; however, in all cases, therapeutic intervention must be aggressive regardless of whether microalbuminuria is present or not. It is not recommended to measure UAE in non-diabetic non-hypertensive subjects in the absence of history of renal disease. Monitoring of renal function (UAE, serum creatinine and estimation of GFR) is recommended annually in all subjects with microalbuminuria.

MANAGEMENT

In patients with microalbuminuria, weight reduction, sodium restriction (<6 g per day), smoking cessation, strict glucose control in diabetic subjects, strict arterial pressure control are necessary; in diabetic subjects: use of maximal doses of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) are recommended; ACEI/ARB and thiazides have synergistic actions on arterial pressure and reduction of UAE; in non-diabetic subjects, any of the five classes of anti-hypertensive medications (ACEI, ARB, thiazides, calcium channel blockers or beta-blockers) can be used.

Efeitos fisiológicos do treinamento físico em pacientes portadores de diabetes tipo 1

Insulinoterapia, atividade física regular e planejamento alimentar, em conjunto, consistem na abordagem mais completa no tratamento de portadores de diabetes mellitus tipo 1 (DM1). Estudos clínicos e experimentais têm evidenciado os benefícios do treinamento físico em indivíduos com DM1, tais como melhora na sensibilidade à insulina, redução das doses de insulina e atenuação das disfunções autonômicas e cardiovasculares. Essa revisão aborda as adaptações fisiológicas ao treinamento físico no indivíduo com DM1 e discute as recomendações e prescrição de atividade física para esta população.

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.

Effects of Exercise Training on Glomerular Structure in Fructose-Fed Spontaneously Hypertensive Rats

A high-fructose diet (HFD) has been shown to elevate blood pressure (BP) and to decrease insulin sensitivity in rats. Although running exercise can attenuate these phenomena, its effect on target organ protection is not clear. We investigated whether exercise training has renal protective effects in this model. Nine-week-old spontaneously hypertensive rats were allocated to groups that received HFD or a control diet (control group) for 15 weeks. At the age of 10 weeks, fructose-fed rats were allocated to groups that were given vehicle (FRU group), temocapril, an angiotensin converting enzyme inhibitor (TEM group), exercise training (EX group; treadmill running), or temocapril plus exercise training (TEM+EX group). BP was higher in the FRU group than in the control group. Exercise training tended to decrease BP and temocapril treatment decreased BP significantly. Proteinuria was similar in the five groups. Plasma leptin concentration and epididymal fat weight were lower in the EX and TEM+EX groups than in the FRU group. In the soleus muscle of the FRU group, the composite ratio of type I fiber was decreased and that of type IIa fiber was increased compared with those in the control group. Both temocapril and exercise training restored these ratios. The glomerular sclerosis index (GSI) was higher in the FRU group than in the control group. GSI was decreased equally in the TEM, EX, and TEM+EX groups and was positively correlated with plasma leptin concentration. The results suggest that exercise training ameliorates glomerular sclerosis through mechanisms other than a reduction in BP.

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.

Do obesity and non-insulin dependent diabetes mellitus aggravate exercise-induced microproteinuria?

We evaluated the role of obesity in proteinuria by treadmill exercising of simple obese subjects and non-obese subjects with non-insulin dependent diabetes mellitus in whom the albumin excretion rate at rest was within normal range. Non-obese healthy volunteers were studied as the controls. The fractional renal clearances of four endogenous proteins, albumin, IgG, IgG4, and beta2-microglobulin were measured before, during, and after treadmill exercise in 17 simple obese and 15 non-obese diabetic subjects, and in 21 normal subjects. Exercise increased the fractional albumin clearance in all groups. In diabetic subjects, the fractional IgG4 clearance also increased: fractional beta2-microglobulin clearance increased in normal controls and in diabetics. In obese subjects, the fractional clearances of albumin, IgG, and IgG4 were similar to those in normal controls, but fractional beta2-microglobulin clearance was significantly lower. These results suggest that enhanced microalbuminuria in obese subjects is probably of glomerular origin. In normal subjects and diabetics, exercise-induced microproteinuria is probably of both glomerular and tubular origin. Defect in the charge-selective barrier of the glomerular capillary wall has been implicated in diabetics. Thus some additional factors relevant to obesity must be taken into account in the consideration of the mechanism of microalbuminuria in diabetics with obesity.

Decrease of exercise-induced microalbuminuria in patients with type I diabetes by means of an angiotensin-converting enzyme inhibitor

Taking into account both the importance of microalbuminuria (MA) as a predictive parameter of clinical nephropathy in diabetic patients and the efficiency of exertion to show and/or to increase MA in both diabetic patients and normal individuals, we studied 37 type I diabetic patients divided into two groups: group A, with no MA at rest (n = 19), and group B, with MA at rest (n = 18). Group C comprised 10 healthy volunteers as controls. Changes of basal MA during exercise and postexercise were studied in all three groups. Normotensive patients with no metabolic disorders, normal renal function, and no proteinuria underwent an ergometric test up to 600 kg. This test was repeated after the administration of 20 mg enalapril in a single daily dose for 60 days. Body weight, systolic and diastolic arterial pressure, creatinine, and creatinine clearance were determined and showed no significant variations either between groups or with treatment. Microalbuminuria was studied in the three groups with and without administration of enalapril throughout the 2 months of the study. Determinations were performed under conditions of rest, exercise, and postexercise. Mean baseline MA values +/- SEM were as follows: at rest, 5.22 +/- 0.49, 58.36 +/- 13.24, and 4.73 +/- 0.45 micrograms/min for groups A, B, and C, respectively; with exercise, 15.19 +/- 4.43, 74.70 +/- 14.89, and 16.76 +/- 4.62 micrograms/min for groups A, B, and C, respectively; and postexercise, 32.04 +/- 6.64, 253.15 +/- 63.88, and 9.23 +/- 3.25 micrograms/min, respectively. The geometric means of the baseline to posttreatment MA ratio were as follows: at rest, 0.95, 1.59 (P < 0.01), and 1.03 for groups A, B, and C, respectively; with exercise, 1.53 (P < 0.01), 1.91 (P < 0.01), and 1.69 for groups A, B, and C, respectively; and postexercise, 2.94 (P < 0.01), 3.24 (P < 0.01), and 1.03 for groups A, B, and C, respectively. In conclusion, in the early diagnostic suspicion of diabetic nephropathy, the screening of postexercise MA during an ergometric test could be of help. Treatment with enalapril decreased MA in diabetic groups A (no MA at rest) and B (MA at rest) during exercise and postexercise, and also decreased MA in group B while at rest.

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.

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.

Glomerular filtration and tubular reabsorption of albumin in preproteinuric and proteinuric diabetic rats

Microalbuminuria (26-250 mg/d) is considered to be an indicator of incipient diabetic nephropathy in humans in insulin-dependent diabetes (IDD). However, before microalbuminuria is observed, glomerular alterations, such as glycosylation of the glomerular basement membrane and glomerular hyperfiltration, in IDD may result in increased filtration of albumin before any observed increase in albumin excretion. Glomerular and tubular albumin kinetics were examined in streptozotocin (65 mg/kg body wt, i.v.) diabetic, Munich-Wistar rats at 7-10 (untreated) and 50-70 d (poorly controlled with small doses of insulin) after the onset of diabetes and compared with nondiabetic controls. Additional rats in each condition received acute lysine treatment to prevent tubular protein reabsorption. Urinary albumin excretion and nonvascular albumin distribution volumes were measured in the renal cortex and compared with morphometric measurements of interstitial space and the proximal tubule to assess intracellular uptake of albumin in the proximal tubule. Urinary albumin excretion under anesthesia was not different in 7-10-d IDD versus controls (19 +/- 3 vs. 20 +/- 3 micrograms/min) but increased in the 50-70-d IDD (118 +/- 13 micrograms/min, P < 0.05). Lysine treatment resulted in increased albumin excretion compared with respective nontreatment in 7-10-d IDD (67 +/- 10 micrograms/min, P < 0.05) but not in controls (30 +/- 6 micrograms/min) or in 50-70-d IDD (126 +/- 11 micrograms/min). Glomerular filtration rate was increased both in 7-10-d IDD (2.7 +/- 0.1 ml/min, P < 0.05) and in 50-70-d IDD (2.6 +/- 0.1 ml/min, P < 0.05) compared with control (2.2 +/- 0.1 ml/min). Calculated urinary space albumin concentrations increased early in IDD with 2.5 +/- 0.4 mg% in 7-10-d IDD and 4.9 +/- 0.6 mg% in 50-70-d IDD compared with control (1.4 +/- 0.3 mg%). The increase in filtration of albumin is in excess of that attributable to hyperfiltration before increased albumin excretion early in diabetes. In 50-70-d IDD, absolute tubular reabsorption of albumin is decreased, correlating to the decrease in brush border height of the proximal tubule.

Intensity-related exercise albuminuria in insulin dependent diabetic patients

Normoalbuminuric insulin-dependent diabetic (IDDM) patients may present higher rates of urinary albumin excretion after submaximal exercise at a standard intensity. To evaluate whether the urinary albumin excretion of IDDM patients is increased after maximal and submaximal exercise when exercise intensities are adjusted according to individual lactate thresholds, 16 normoalbuminuric IDDM patients (mean time from diagnosis 8 years) and 13 normal controls exercised for 20 min at intensities corresponding to 90% of the first and second lactate thresholds and to maximal tolerance on different days. Urinary albumin excretion, blood lactate concentration, heart rate and blood pressure were measured. Metabolic and cardiovascular responses to submaximal and maximal exercise were similar for patients and controls. After exercise at 90% of the first lactate threshold neither patients or controls demonstrated significant changes in urinary albumin excretion. After exercise at 90% of the second lactate threshold both patients and controls demonstrated a similar increase in urinary albumin excretion. After maximal exercise both patients and controls demonstrated marked and similar elevation in the urinary albumin excretion. There was a significant correlation (r = 0.74, P < 0.001) between blood lactate levels at the end of exercise and the decimal logarithm of post-exercise urinary albumin excretion of the diabetic patients. Thus, when exercise intensities are adjusted for lactate thresholds, normoalbuminuric IDDM patients present normal intensity-related urinary albumin excretion during exercise. These data suggest that previously observed differences in exercise induced albuminuria in IDDM patients might be related to inappropriate standardization of submaximal exercise intensities.

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.

Kidney function in newly diagnosed type 2 (non-insulin-dependent) diabetic patients, before and during treatment

Glomerular filtration rate, kidney volume, and urinary albumin excretion rate were studied in otherwise healthy newly diagnosed Type 2 (non-insulin-dependent) diabetic patients, untreated at diagnosis, after short-term treatment and after 3 months treatment. In 10 patients (Group A) glomerular filtration rate (measured by the plasma clearance of 51-Cr-EDTA) decreased from the time of diagnosis 106.2 +/- 14.6 ml.min-1.1.73 m2(-1) (mean +/- SD) to 95.9 +/- 13.7 ml.min-1.1.73 m2(-1) after 3 months treatment (p = 0.049). At the same time, mean plasma glucose was reduced from 13.3 +/- 3.2 mmol/l to 6.5 +/- 1.1 mmol/l. The fall in mean plasma glucose was correlated to the reduction in glomerular filtration rate, r = 0.76, p = 0.011. Kidney volume as measured by ultrasonic scanning was reduced from 264.0 +/- 33.7 ml/1.73 m2 to 210.8 +/- 23.8 ml/1.73 m2 (p less than 0.005). The relative decline in urinary albumin excretion rate was correlated to the fall in glomerular filtration rate, r = 0.69, p = 0.026. In 15 patients (Group B) 24-h urine collections were made during 9.5 +/- 3.2 days, urinary albumin excretion rate fell from the first to the last day in hospital from 14.0 x/divided by 3.0 micrograms/min (geometric mean x /divided by tolerance factor) to 7.0 x/divided by 2.7 micrograms/min p = 0.015. The relative decline was correlated to the change in mean plasma glucose, r = 0.65, p = 0.032. Thus, kidney function in Type 2 diabetic patients is influenced by metabolic control, although to a lesser extent than is seen in Type 1 (insulin-dependent) diabetic patients with comparable glycaemic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between urinary albumin excretion rate and renal histology in non-insulin-dependent diabetes mellitus: with reference to the clinical significance of microalbuminuria

The present study demonstrates the relationship between urinary albumin excretion rate (AER) and renal structural changes in patients with non-insulin-dependent diabetes mellitus (NIDDM) without clinical proteinuria. Resting AER in 30 control subjects and 67 NIDDM patients were 10.4 +/- 4.8 (mean +/- SD) micrograms/min (range 4.3-21.1 micrograms/min) and 26.4 +/- 32.3 micrograms/min (range 0.4-155 micrograms/min), respectively. Persistent normoalbuminuria (less than 20 micrograms/min) and microalbuminuria (20-200 micrograms/min) were found in 43 (Group A) and 24 (Group B) diabetics. There were significant differences in age, diabetes duration, and frequency of retinopathy (background and proliferative) as well as that of proliferative retinopathy between Groups A and B, but not in the other clinical parameters such as body mass index, HbA1, Ccr, or systolic and diastolic blood pressure (SBP, DBP). When compared with 11 normoalbuminuric patients of similar age and equal diabetes duration to those in Group B, the sole difference in clinical parameters was the existence of proliferative retinopathy in Group B. Renal structural changes were investigated by light microscopy in 14 people in Group A and 13 people in Group B, and additionally in 5 NIDDM patients with both macroalbuminuria (greater than or equal to 200 micrograms/min) and normal or nearly normal renal function (Group C). The diffuse glomerular lesion (Gellman's classification) was grade I or II in A, II or III in B, and III in C.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary albumin excretion in diabetic pregnancy

We have analysed the results of urinary albumin excretion in timed overnight urine samples once every two weeks during pregnancy and post-natally in 25 non-diabetic women and 14 women with Type 1 (insulin-dependent) diabetes who were Albustix negative and had urinary albumin excretion less than 15 micrograms.min-1 at conception. Urinary albumin excretion did not vary significantly in the first two trimesters in either group and at 28 weeks was 2.73 micrograms.min-1 (0.32-251.68) (median and range) in the diabetic women and 2.53 micrograms.min-1 (0.90-13.37) in control patients (not significant). During the third trimester urinary albumin excretion increased, and levels were significantly higher in diabetic patients from 36 weeks (9.37 (0.9-31.78) vs 3.52 (0.19-33.74) micrograms.min-1, p less than 0.01) until delivery. In both groups, urinary albumin excretion reached a peak within the week following delivery - diabetic 17.42 micrograms.min-1 (2.03-46.64), control subjects 16.29 micrograms.min-1 (1.53-35.56), but six weeks after delivery, levels were similar to those in early pregnancy. The effect of pregnancy on urinary albumin excretion in these diabetic women would appear to be an exaggeration of the normal pattern, with levels returning to normal post-delivery. It is not possible to know if this has significance for future renal function, but it would be important to investigate this phenomenon in patients who already have raised urinary albumin excretion at conception.

Short term effect of captopril on microalbuminuria induced by exercise in normotensive diabetics

OBJECTIVE

To investigate whether captopril has any effect on microalbuminuria induced by exercise in normotensive diabetic patients with early stage nephropathy.

DESIGN

Randomised, double blind, crossover trial.

SETTING

Outpatient department.

PATIENTS

22 diabetics with stage II nephropathy (urinary albumin excretion rate less than 20 micrograms/min; 15 with type I diabetes and seven with type II), 32 patients with stage III nephropathy (urinary albumin excretion rate 20-200 micrograms/min; 14 with type I diabetes and 18 with type II), and 10 normal subjects.

INTERVENTIONS

Four exercise tests on a cycle ergometer: the first two under basal conditions and the third and fourth after subjects had received captopril (two 25 mg doses in 24 hours) or placebo (two tablets in 24 hours).

END POINT

Exercised until 90% of maximum heart rate achieved.

MEASUREMENTS AND MAIN RESULTS

Mean urinary excretion one hour after the first two exercise tests was 21 micrograms/min in normal subjects, 101 micrograms/min in diabetic patients with stage II nephropathy, and 333 micrograms/min in those with stage III nephropathy. Similar results were obtained after placebo. After captopril the urinary excretion rate one hour after exercise was significantly decreased in diabetics with stage II (36 micrograms/min) and stage III (107 micrograms/min) disease compared with placebo but not in normal subjects. Systolic and diastolic pressures were similar in the three groups after placebo and captopril had been given.

CONCLUSIONS

Captopril significantly reduces microalbuminuria induced by exercise in normotensive diabetics without affecting systemic blood pressure. Captopril may reduce renal intracapillary pressure.

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.

Tubular dysfunction and microalbuminuria in insulin dependent diabetes

The nature of microproteinuria in the early years of insulin-dependent diabetes was investigated in a cross sectional study of 80 children with insulin-dependent diabetes and 40 normal children. Urinary excretion of three low molecular weight proteins: alpha-1-microglobulin, beta-2-microglobulin and kappa light chains was used as an index of proximal renal tubular function. The first urine samples of the morning were collected and excretion of proteins measured was expressed as ratio of protein to creatinine. There was a strong correlation between excretion of alpha-1-microglobulin and chi light chains and their excretion was significantly higher in diabetic children indicating decreased proximal tubular reabsorbtion. The excretion of beta-2-microglobulin was found to be an unsatisfactory index of proximal tubular function. Urinary albumin excretion was not significantly raised in diabetic children and did not correlate with urinary alpha-1-microglobulin or chi light chain excretion. Glycaemic control might influence proximal tubular function as both urinary glucose concentration and glycosylated haemoglobin showed correlations with urinary alpha-1-microglobulin excretion and with urinary chi light chain excretion.

Hematuria and microalbuminuria after a 100 kilometer race

An investigation into hematuria and microalbuminuria induced by prolonged physical exercise was carried out by studying 26 runners who took part in a 100 km race by collecting urine samples before, after the race, and 24 hours later. Microscopic hematuria was present in two runners before the race. After this strenuous exercise there was macroscopic hematuria in five runners (19.2%) and microscopic hematuria in nine (34.6%). On examination by phase contrast microscopy there were neither dysmorphic erythrocytes nor red cell casts. Albuminuria was measured by radial immunodiffusion and was expressed as Ualb/Ucreat and Ualb/Uosm ratios. Clinical albuminuria was found in five runners with macroscopic hematuria, and microalbuminuria in 13 of the 21 remainders; in 6 of them it was associated with microscopic hematuria. Twenty-four hours later all of the results were normal with the exception of the five runners who have had macroscopic hematuria and another one with microalbuminuria without hematuria. We conclude that determination of albumin excretion in runners after exercise should be made as well as hematuria, and particular attention should be paid to cases of severe and/or prolonged microalbuminuria, since such individuals may be at risk of renal disease.

Variability of albumin excretion in insulin-dependent diabetics

Sixteen adults patients with insulin-dependent diabetes mellitus and 16 healthy controls, matched for sex and age, were asked to collect their urine during the night and during the day at rest, at weekly intervals on four occasions. Subjects with heart failure, kidney disease, hypertension, abnormal urinalysis (Albustix positive) or poorly controlled diabetes prior to entry in the study, were excluded. A high variability in the albumin excretion rates (AER) was observed in both diabetic and control groups but the variance was significantly greater in diabetics. Moreover the variance in AER was higher in daytime as compared to overnight urine collections in both groups. Overnight urine collections are more precise than daytime urine collections for the determination of AER.

[Radioimmunoassay of urinary albumin: early indicator of diabetic nephropathy?]

Microalbuminuria is now considered a good biological marker predictive of diabetic nephropathy. The degree of microalbuminuria was determined by radioimmunoassay in 23 controls and 50 insulin-dependent patients with poor control of glycaemia. Higher levels were found in diabetics, whatever the duration of the disease. At the moment, this difference, which is reversible with good metabolic control, can be explained by blood glucose balance. Several authors have established the existence of a microalbuminuria threshold predictive of nephropathy, but its level is controversial, chiefly on account of the urine collection methods.

Screening for early diabetic nephropathy: which sample to detect microalbuminuria?

In a study to monitor the acceptability of using a timed overnight urine collection to measure microalbuminuria in a large diabetic population, it was found that only 184 (69.4%) of 265 diabetics returned the urine collection to the hospital laboratory. Three proposals for an initial screening test to predict high risk microalbuminuria were analysed. Proposal I: a random urinary albumin concentration (RAC) greater than 25 micrograms/ml predicts an overnight albumin excretion rate (AER) greater than 30 micrograms/min. In 159 diabetics, the sensitivity of this screening test was 56%, specificity 81%, and predictive value 15%. Proposal II: an albumin concentration greater than 20 micrograms/ml in an early morning urine sample predicts an overnight AER greater than 30 micrograms/min. In 175 diabetics, the sensitivity of this screening test was 86%, specificity 97%, and predictive value 71%. Proposal III: an albumin/creatinine ratio (albumin mg/l creatinine mmol/l) greater than 3.5 in an early morning urine sample predicts an overnight AER greater than 30 micrograms/minute. In 171 diabetics, the sensitivity of this screening test was 100%, specificity 95%, and predictive value 64%. It is concluded that an albumin/creatinine ratio performed on an early morning urine sample brought to the diabetic clinic would be a useful initial screening test to detect an overnight AER greater than 30 micrograms/min.

Predicting diabetic nephropathy in insulin-dependent patients

We studied whether microalbuminuria (urinary albumin excretion rates of 15 to 150 micrograms per minute) would predict the development of increased proteinuria in Type I diabetes. We also studied the influence of glomerular filtration rate, renal blood flow, and blood pressure on the later development of proteinuria. Forty-four patients who had had Type I diabetes for at least seven years and who had albumin excretion rates below 150 micrograms per minute were studied from 1969 to 1976, and 43 were restudied in 1983. Of the 14 who initially had albumin excretion rates at or above 15 micrograms per minute, 12 had clinically detectable proteinuria (over 500 mg of protein per 24 hours) or an albumin excretion rate above 150 micrograms per minute at the later examination. Of the 29 who initially had albumin excretion rates below 15 micrograms per minute, none had clinically detectable proteinuria at the later examination, although four had microalbuminuria. Those whose condition progressed to clinically overt proteinuria had elevated glomerular filtration rates and higher blood pressures at the initial examination than did those in whom proteinuria did not develop. Renal blood flow was not elevated in these patients. We conclude that microalbuminuria predicts the development of diabetic nephropathy and that elevated glomerular filtration rates and increased blood pressure may also contribute to this progression.

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

The aim of the study was to evaluate the influence of light to moderate dynamic work (450 kpm/min followed by 600 kpm/min during 20 min each) on the blood pressure and renal protein handling in insulin-dependent diabetic patients with incipient nephropathy (D3) (elevated baseline albumin excretion but without clinical proteinuria). Fifteen male diabetic patients (D3) with a mean age of 26.5 +/- 4.8 years (SD) and a diabetes duration of 15.6 +/- 3.4 years (SD), 11 comparable diabetic patients with normal urinary albumin excretion (D2), and ten non-diabetic subjects (C) were studied. In D3 baseline diastolic blood pressure was elevated [92.1 mm Hg +/- 6.0 (mean +/- SD)] compared to D2 (80.9 mm Hg +/- 4.8, 2P = 0.003%) and C (79.5 mm Hg +/- 12.4, 2P = 1.2%). Baseline systolic blood pressure was not significantly different in the three groups, but systolic blood pressure was more elevated at 600 kpm/min in D3 (193.0 mm Hg +/- 23.0) compared to D2 (170.5 +/- 17.3, 2P = 1.2%) and C (157.5 mm Hg +/- 20.9, 2P = 0.07%). Baseline albumin excretion in D3 was 82.6 micrograms/min X/ divided by 2.5 (geometric mean X/ divided by tolerance factor) and during exercise the maximal albumin excretion rose to 195.0 micrograms/min X/ divided by 2.6 (2P = 0.01%). In D2 albumin excretion rose from 3.3 micrograms/min X/ divided by 1.9 to 7.9 micrograms/min X/ divided by 1.5 (2P = 0.02%). The albumin excretion in C did not change during exercise. A highly significant correlation between maximal exercise induced systolic blood pressure and maximal exercise induced albumin excretion was demonstrable in D3.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of metabolic control and duration on exercise-induced albuminuria in diabetic teen-agers

Nineteen type I diabetic teen-agers without clinical signs of nephropathy with a duration of diabetes varying from 3 to 16.8 years were examined by a standardized exercise test for analysis of urinary excretion of albumin and beta 2-microglobulin. The patients were studied both in poor and improved (but not perfect), metabolic control as defined by HbA1c and blood glucose profiles, and the values were compared to those of 14 age-matched healthy controls. The controls showed no increase in albumin excretion rate during exercise as was found in diabetic patients. The albumin excretion rate during exercise was significantly correlated (p less than 0.05) to systolic blood pressure in the diabetic patients. Blood pressure in the diabetic patients was, however, similar to that of controls both at rest and during exercise. Urinary beta 2-microglobulin did not change during exercise. The urinary albumin excretion during exercise decreased significantly with improved metabolic control in diabetic patients, but the albumin excretion rate was not correlated with either blood or urinary glucose or diuresis during the exercise test. When metabolic control was improved there was a significant correlation between the increase in albumin excretion rate during exercise and the duration of diabetes, indicating that part of the exercise-induced albumin excretion might reflect irreversible morphological changes in the diabetic kidney. This test might therefore have a predictive value for diabetic nephropathy if performed during strict metabolic control.