Pancreatic beta-cell function in cirrhotic patients with and without overt diabetes. C-peptide response to glucagon and to meal

To study the role of pancreatic beta-cell function in glucose intolerance and frank diabetes that sometimes develops in cirrhosis, the C-peptide response to a bolus IV injection of 1 mg of glucagon was measured in nine controls and in two groups of patients with cirrhosis. The first group comprised nine subjects with normal or high-normal fasting plasma glucose and no glycosuria; five of them had impaired glucose tolerance. The second group consisted of eight cirrhotics in whom frank diabetes had developed six to 48 months after the diagnosis of cirrhosis. They were characterized by fasting plasma glucose greater than 140 mg/dL and permanent glycosuria. No differences in the degree of liver impairment or portal-systemic shunting were observed between the two groups. Plasma glucose response to glucagon was similarly reduced in cirrhotic subjects. Basal C-peptide was high normal in patients with cirrhosis, and significantly increased in nondiabetic subjects. By contrast peak C-peptide levels and total C-peptide responses to glucagon were low normal in cirrhotics and significantly reduced in patients with cirrhosis and diabetes. In 14 patients the C-peptide response to a standard meal was also measured. It was significantly reduced in patients with cirrhosis and diabetes (six cases), as compared to cirrhotic subjects without diabetes. Peak C-peptide after IV glucagon significantly correlated with peak C-peptide after the meal (r = .927), or total C-peptide response to meal (r = .871). Impaired insulin secretion may add to insulin resistance in patients with liver cirrhosis, leading to the development of frank diabetes, characterized by fasting hyperglycemia and glycosuria.     

Prevalence of residual B-cell function in insulin-treated diabetics evaluated by the plasma C-peptide response to intravenous glucagon

Summary In 83 insulin-treated diabetics the influence of the duration of insulin treatment on the prevalence of residual insulin secretion was examined by determining the plasma C-peptide concentration before and after intravenous injection of 1 mg of glucagon. In 64 patients, plasma C-peptide concentration was also determined before and after a standard meal. There was a good correlation between the C-peptide response to glucagon and to the meal (r=0.67; p<0.0001) suggesting that the glucagon test will predict the B-cell response during everyday life. The predictive value of a positive glucagon test was 84% and of a negative test 100%. A preserved, but reduced, B-cell function was demonstrable in 36 of 83 patients. Residual B-cell function was most frequent in the patients with the shortest duration of diabetes. The metabolic importance of endogenous insulin was demonstrated by the significantly lower insulin requirement in the patients with residual B-cell function.     

Serum free C-peptide response to oral glucose loading as a parameter for the monitoring of pancreatic B-cell function in diabetic patients

As a parameter for evaluating pancreatic B-cell function, the accuracy of measuring serum free C-peptide immunoreactivity (CPR) was compared with that of measuring plasma immunoreactive insulin (IRI) and urine CPR in diabetic patients during a 100 g oral glucose tolerance test. In 25 non-obese patients receiving oral hypoglycemic agent or diet treatment alone, a positive correlation between the sum of serum free CPR (sigma serum free CPR) and the sum of plasma IRI (sigma plasma IRI) was noted (r = 0.68, P less than 0.001). However, the sum of blood glucose values was found to be negatively correlated to sigma free CPR (r = -0.56, P less than 0.0025), but not to sigma plasma IRI (r = -0.25, NS). In 23 patients receiving diet, oral hypoglycemic agent or insulin treatment, a positive correlation between sigma serum free CPR and urine CPR was noted (r = 0.75, P less than 0.001). However, no significant correlation was found when only insulin-treated patients were investigated (r = 0.37, NS, n = 17). In addition, patients with insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus were better differentiated by measuring sigma serum free CPR than urine CPR. Thus, we concluded that the measurement of serum free CPR during OGTT provides an extremely valuable method for monitoring pancreatic B-cell function in diabetic patients, whether they are receiving insulin treatment or not.     

糖尿病患者血清基质金属蛋白酶-9、尿白蛋白排泄率与血管内皮功能的关系

目的 观察糖尿病患者不同程度尿白蛋白排泄率、基质金属蛋白酶-9（MMP-9）对血管内皮功能的影响.方法 将90例糖尿病患者按照24小时尿白蛋白排泄率分为正常蛋白尿组、微量白蛋白尿组和大量白蛋白尿组,记录其病程,通过调查问卷调查近3天的饮食情况并输入“开同食谱计算器”,估算其每日蛋白摄入量的平均值.空腹采血测定血糖、糖化血红蛋白、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇和MMP-9浓度,通过超声测定其肱动脉血管内径、基础血流、内皮依赖性血管舒张功能及硝酸甘油介导的血管舒张功能,通过99mTc-二已三胺乙酸ECT法测定肾小球滤过率,并与30名同期体检的健康人群进行比较.结果 随尿白蛋白排泄率升高,3组糖尿病患者糖化血红蛋白、三酰甘油、MMP-9浓度升高（P＜0.05）,而高密度脂蛋白胆固醇、肾小球滤过率下降（P＜0.05）,内皮功能逐渐减退,与对照组比较,微量和大量白蛋白尿组内皮依赖性血管内径变化率明显降低（P＜0.05）.所有患者饮食中日均蛋白质摄入量均超过1 g/kg.结论 随糖尿病患者尿白蛋白排泄率增加,进行性出现MMP-9升高,血管内皮功能紊乱,而糖尿病患者未能严格落实饮食中蛋白质摄入的管理.     

老年早期糖尿病肾病患者尿白蛋白排泄率相关因素分析

目的探讨2型糖尿病早期肾病的危险因素与防治策略。方法以2型糖尿病早期肾病老年患者(DN组)73例,2型糖尿病无肾病患者(DM组)35例为研究对象,测定炎症指标血清炎症因子超敏C反应蛋白(hs-CRP)、肿瘤坏死因子α(TNF-α)、白细胞介素-6(IL-6)、白细胞介素-1β(IL-1β)水平、生化指标空腹血糖(FBG)、餐后2 h血糖(PBG)、糖化血红蛋白(Hb A1c)、血脂[总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL)、低密度脂蛋白(LDL)]、尿酸(UA)、空腹胰岛素(FINS)。计算胰岛素抵抗指数(HOMA-IR)、尿白蛋白排泄率(UAER);测量身高、体重、血压。结果 DN组血清炎症因子hs-CRP、TNF-α、IL-6、IL-1β水平及LDL、UA、Hb A1c、FINS、HOMA-IR比DM组升高(P0.05)。相关分析显示,UAER与TNF-α、IL-6、HOMA-IR呈正相关(r=0.549、0.584、0.894,P0.01)。结论早期2型糖尿病肾病患者尿白蛋白排泄率与炎症状态、胰岛素抵抗相关。     

Residual B cell function in diabetic children as determined by urinary C-peptide

Summary C-peptide was determined in 24-h urine collections and in fasting plasma of 27 Type 1 (insulin-dependent) diabetic children (duration of disease 0–6 years) and in 11 matched normal children. Grouping the patients according to duration of disease from onset to 6 years, it was found that in the first year of disease the B cell reserve was a mean of 4.89±1.95 pmol · mg creatinine^-1. 24 h^-1 compared with a mean of 24.51±2.91 pmol · mg^-1 · 24 h^-1 in the control group. A further diminution was seen with increase in the duration of disease, until after 6 years when only traces of C-peptide could be detected. There was a good correlation between the levels of plasma C-peptide and urinary C-peptide values as related to creatinine (r = 0.89; p = < 0.001). In view of this, and since it is simpler and less traumatic to obtain frequent urine samples from children than it is to obtain blood samples, it was felt that the determination of urinary C-peptide constitutes a valuable tool in the evaluation of the diabetic child.     

A comparison of serum C-peptide response to intravenous glucagon, and urine C-peptide, as indexes of insulin dependence

Serum C-peptide (SCPR) at fasting and after intravenous injection of glucagon was evaluated in diabetic patients with various degrees of insulin dependence, and compared with 24 h urine C-peptide (UCPR). Fasting SCPR did not differ between healthy subjects and sulfonylurea-treated patients (SU) who were considered to have definite non-insulin-dependent diabetes (NIDDM); but was significantly lower in patients with insulin-dependent diabetes (IDDM) (0.24 +/- 0.10 ng/ml in IDDM vs. 1.43 +/- 0.61 ng/ml in SU, P less than 0.001). SCPR reached a peak at 6 min after glucagon injection, except for the IDDM group. The SCPR response at 6 min after 1 mg glucagon injection was significantly lower in the SU (NIDDM) group than in the normal group (2.86 +/- 1.21 v. 4.69 +/- 1.47 ng/ml, P less than 0.001). In the IDDM group, there was no increase of SCPR after glucagon injection. Among diabetic patients, SCPR response to glucagon correlated positively to the amounts of UCPR (P less than 0.001). By analysis of the distribution patterns of SCPR response to intravenous glucagon, SCPR of 1.0 ng/ml and the increment of SCPR of 0.5 ng/ml at 6 min are to be used as cut-off points to differentiate IDDM and NIDDM. These values correspond roughly to the UCPR values below 20 micrograms/day and above 30 micrograms/day, which we previously proposed as indexes to differentiate insulin-dependent and non-insulin-dependent diabetes.     

Ingestion of a mixed meal does not affect the metabolic clearance rate of biosynthetic human C-peptide

The validity of C-peptide as a peripheral marker of insulin secretion during different physiological conditions depends on the demonstration that C-peptide clearance is constant under these circumstances. Recently biosynthetic human C-peptide, identical in structure to pancreatic human C-peptide, became available for use in human subjects. The present study was undertaken to determine if the metabolic clearance of C-peptide was altered by ingestion of a mixed meal. Eight insulin-dependent diabetic patients received constant iv infusions of biosynthetic human C-peptide which raised the plasma C-peptide concentration to a level of 3.8 +/- 0.2 (+/- SEM) pmol/ml. The MCR of C-peptide was 4.5 +/- 0.3 ml/kg X min. After steady state levels of C-peptide had been reached, each patient consumed a 530 calorie mixed meal. The plasma glucose concentration increased from a baseline value of 104.5 +/- 4.8 mg/dl to a 336 +/- 10 mg/dl 150 min later. This change in plasma glucose was not associated with a significant alteration in the plasma C-peptide concentration and the MCR of the infused C-peptide was not affected by meal ingestion (4.5 +/- 0.3 vs. 4.3 +/- 0.3 ml/kg X min). These results therefore support the validity of using C-peptide as a marker for changes in insulin secretion after mixed meals.     

替米沙坦对尿白蛋白排泄率正常的糖尿病患者肾小球滤过率的影响

目的 研究替米沙坦对尿白蛋白排泄率(UAER)正常的DM患者肾小球滤过率(GFR)的影响.方法 113例UAER正常的DM患者,口服替米沙坦40mg/d,9～14周,分析治疗前后GFR的变化.结果 治疗前DM组的GFR高于对照组(P<0.01);治疗后DM组GFR较治疗前降低(P<0.01);治疗后GFR下降者治疗前的GFR高于非下降者.结论 替米沙坦能有效改善UAER正常的DM患者的高GFR状态,对DM患者的肾脏有保护作用.     

Fasting plasma C-peptide,glucagon stimulated plasma C-peptide,and urinary C-peptide in relation to clinical type of diabetes

Summary Many patients with Type 2 (non-insulin-dependent) diabetes mellitus are treated with insulin in order to control hyperglycaemia. We studied fasting plasma C-peptide, glucagon stimulated plasma C-peptide, and 24 h urinary C-peptide in relation to clinical type of diabetes in 132 insulin treated diabetic subjects. Patients were classified clinically as Type 1 (insulin-dependent) diabetic subjects in the presence of at least two of the following criteria: 1) significant ketonuria, 2) insulin treatment started within one year after diagnosis, 3) age of diagnosis 40 years, and 4) weight below 110% of ideal weight of the same age and sex. Eighty patients were classified as Type 1 and 52 as Type 2 diabetic subjects. A second classification of patients into 6 C-peptide classes was then performed. Class I consisted of patients without islet B-cell function. Class II-VI had preserved islet B-cell function and were separated according to the 20%, 40%, 60% and 80% C-peptide percentiles. The two classifications of patients were compared by calculating the prevalence of clinical Type 1 and Type 2 diabetes in each of the C-peptide classes. This analysis showed that patients with a fasting plasma C-peptide value <0.20 nmol/l, a glucagon stimulated plasma C-peptide value <0.32 nmol/l, and a urinary C-peptide value <3.1 nmol/l, or <0.54 nmol/mmol creatinine/24 h, or <5.4 nmol/24 h mainly were Type 1 diabetic patients; while patients with C-peptide levels above these values mainly were Type 2. At these limits the percentage, predictive value of positive tests as indicators of Type 2 diabetes were as follows: fasting C-peptide 83%, stimulated C-peptide 86%, and urinary C-peptide expressed as nmol/l 76%, as nmol/mmol creatinine/24 h 79%, and as nmol/24 h 78%. Similarly, the percentage predictive value of negative tests as indicators of Type 1 diabetes were as follows: fasting C-peptide 86%, stimulated C-peptide 88%, and urinary C-peptide expressed as nmol/l 79%, as nmol· mmol creatinine·24 h 81%, and as nmol/24 h 80%. If patients without detectable C-peptide were excluded, the predictive value of negative tests were as follows: fasting C-peptide 81%, stimulated C-peptide 88%, urinary C-peptide expressed as nmol/l 61%, as nmol/mmol creatinine/24 h 69%, and as nmol/24 h 64%. In conclusion, post glucagon C-peptide gives a good distinction between Type 1 and Type 2 diabetes mellitus in insulin treated diabetes while 24 h urinary C-peptide gives a less sensitive distinction between the clinical types of diabetes.     

Plasma renin activity and urinary kallikrein excretion in response to intravenous furosemide in diabetic patients

Summary The responsiveness of renin-angiotensin and kallikrein-kinin systems to furosemide challenge has been investigated in forty-six diabetic patients (34 NIDDM/12 IDDM), subdivided into Group I (uncomplicated DM), Group II (DM with hypertension), Group III (DM with nephropathy), Group IV (DM with hypertension and nephropathy) and a control group of 10 healthy volunteers. Plasma renin activity (PRA) was estimated by radioimmunoassay in blood samples drawn before and 10 min after furosemide administration (0.5 mg/kg i.v.). Urinary kallikrein levels were measured by bioassay using estrogenized rat uterus preparation in 4h urine samples collected before and after the diuretic. Urinary Na⁺ and K⁺ were also measured. The basal PRA in diabetics was not significantly different from controls, whereas, urinary kallikrein levels were markedly low in all patients. Both PRA and kallikrein levels increased after furosemide in controls while in diabetics this response was severely blunted. In a subset of Group I, a paradoxical fall in PRA and kallikrein levels was noted after furosemide, an effect similar to that observed in patients with nephropathy (Group III). This response in absence of clinical and biochemical parameters of nephropathy indicates early derangement of renal hemodynamic mechanisms heralding the onset of nephropathy.     

Pancreatic polypeptide response to a protein-rich meal in diabetic patients with and without neuropathy

A protein-rich meal and insulin-induced hypoglycemia (ITT) are two of the most important stimuli on pancreatic polypeptide (PP) secretion in diabetic patients. Previous studies have shown a reduced PP response to ITT in diabetic patients with autonomic neuropathy (AN). Twelve patients without AN (mean age 44 +/- 10.8 yr, mean duration of diabetes 11 +/- 5.6 yr), 9 with AN (51.4 +/- 6 yr, 15.8 +/- 6.9 yr) and 9 controls (N) were studied. AN was assessed by the evaluation of the beat-to-beat variation of the heart rate during deep breathing. PP secretion was stimulated by a protein-rich meal (200 g meat, 150 g milk). All insulin-dependent diabetic (IDD) patients lacked circulating PP antibodies. All diabetic patients showed a significant reduction in the early vagal phase compared to controls. This behavior was more evident in diabetic patients with AN and the secondary phase of these two groups overlapped with the response of controls. These data may be explained by the initial alterations of vagal functions not detectable by current methods.     

西洛他唑对2型糖尿病尿白蛋白排泄率的影响

目的探讨西洛他唑治疗2型糖尿病早期肾病的临床疗效.方法将60例血压正常伴微量白蛋白尿的2型糖尿病患者,随机分为两组：治疗组30例,予口服西洛他唑片（50 mg,bid）;对照组30例,予口服安慰剂维生素B1（10 mg,bid）,两组均治疗3个月.观察患者治疗前后尿白蛋白排泄率（UAER）的变化.结果治疗组与治疗前比较,UAER明显下降（P＜0.01）,下降幅度达51.6%,约3%病人仅有轻微头痛反应.对照组治疗前后UAER无明显变化（均P＞0.05）.结论西洛他唑能显著降低糖尿病尿白蛋白的排泄,对糖尿病早期肾病具有治疗作用,且安全性好.     

Clinical application of the 24-H urinary C-peptide excretion rate and its relationship to metabolic control in diabetics

Summary In this study, we evaluated in normal subjects, insulin-dependent (IDD) and non-insulin-dependent (NIDD) diabetics, the diurnal urinary C-peptide excretion rate (CPR-U) and its relationship to serum C-peptide concentration and glucose:C-peptide molar ratio, and to the common parameters of metabolic control. The CPR-U (and CPR-U/g creatinine) were significantly lower in IDD and higher in NIDD compared to control subjects. Moreover, a good and significant correlation with serum C-peptide concentrations and the glucose:C-peptide ratio in diabetic subjects as well as in controls and diabetics considered together was found. A slight but significant correlation was present in diabetic subjects between CPR-U and body mass index (r=0.45), 24-h glycosuria (r=−0.36), HbA1 levels (r=−0.31), post-prandial glucose concentrations (r=−0.26) and per cent glucose variation after each meal (r=−0.34). No differences were found in CPR-U and the degree of metabolic control between obese and non-obese NIDD. In conclusion, CPR-U may be a useful and simple method of defining the secretory activity of the B-cell. Metabolic control in diabetics is slightly correlated to the degree of B-cell function as evaluated by the diurnal excretion rate of C-peptide in urine. Part of this paper was presented at the National Meeting of the Italian Diabetes Association, Bari, May 27–29, 1982.     

Insulin/C-peptide response to intravenous glucagon. A dose-response study in normal and non-insulin-dependent diabetic subjects

The C-peptide and insulin secretory responses to increasing doses of iv glucagon (1, 2, 5, 10 micrograms/kg body weight and 1 mg (only diabetics] were investigated in six lean non-insulin-dependent diabetic patients and six normal subjects, matched for body weight and fasting blood glucose concentrations. A well defined relationship between glucagon dose and the C-peptide/insulin response was observed in both groups. The course of the dose-response curves was significantly different in diabetics. The maximal obtainable C-peptide response (E-max) was reduced to 53% of the response in normal subjects (P = 0.037), and the insulin response was reduced to 52% (P = 0.014). E-max was reached in diabetics with only 10 micrograms/kg of glucagon, whereas higher doses seem to be needed in the control group. However, the glucagon dose causing 50% of E-max (ED50) was not significantly higher. Thus, the widely accepted use of 1 mg of glucagon to test residual beta cell function secures a maximal response of both insulin and C-peptide in non-insulin-dependent diabetic subjects. In addition, our data support the theory that beta cell deficiency is a basic feature of non-insulin-dependent diabetes.     

培哚普利对糖尿病肾病肾小管功能及尿内皮素的影响

目的 观察培哚普利对糖尿病肾病（ＤＮ）肾功能及肾脏内皮素（ＥＴ）代谢的影响,探讨培哚普利防治ＤＮ的机制。方法 ４４例无高血压、持续有微量白蛋白尿的２型糖尿病患者随机分为培哚普利治疗组和常规治疗组。结果培哚普利治疗８周后ＤＮ患者增高的尿白蛋白（Ａ１ｂ）、转铁蛋白（ＴＦ）、ＥＴ排泄分别减少４３．５％、４８．１％、３６．３％（Ｐ〈０．０１）,而常规治疗无明显变化,相关分析示尿Ａ１ｂ降低和尿ＥＴ降低呈正相     

Sensitivity and reproducibility of urinary C-peptide as estimate of islet B-cell function in insulin-treated diabetes

The aims of the present study were to evaluate the ability of urinary C-peptide determination to demonstrate presence of residual insulin secretion, and to evaluate the reproducibility of urinary C-peptide excretion in 125 insulin-treated diabetic patients. C-peptide was determined in two consecutive 24-h urine specimens and related to plasma C-peptide 6 min after the intravenous injection of 1 mg glucagon. The detection limit of C-peptide in plasma was defined analytically (greater than or equal to 0.02 nmol l-1) and from pancreatectomized patients (greater than or equal to 0.06 nmol l-1), and in urine only analytically (greater than or equal to 0.1 nmol l-1). If the analytical detection limit of plasma C-peptide was used as indicator of residual insulin secretion, islet B-cell function was preserved in all patients. In patients with stimulated plasma C-peptide levels from 0.02- less than 0.06 nmol l-1 no increase was found in plasma C-peptide values after stimulation with glucagon. This unresponsiveness of islet B-cells is in good agreement with the existence of a biological detection limit of C-peptide in plasma of 0.06 nmol l-1. Using this biological plasma C-peptide detection limit, 49 of 125 patients were without residual insulin secretion. In contrast to this, only 7 patients were diagnosed as C-peptide nonsecretors using the analytical detection limit of urinary C-peptide. Eighty-four per cent of patients considered to have Type 1 (insulin-dependent) diabetes with a duration of diabetes of more than 15 years had detectable C-peptide in the urine.(ABSTRACT TRUNCATED AT 250 WORDS)     

贝前列腺素钠对早期糖尿病肾病患者尿白蛋白排泄率血清胱抑素C及血管内皮功能的影响

目的：探讨贝前列腺素钠对早期糖尿病肾病患者尿白蛋白排泄率、血清胱抑素C及血管内皮功能的影响。方法选择早期糖尿病肾病患者58例,按随机数字表法分为对照组30例和治疗组28例。对照组予低蛋白饮食、人胰岛素控制血糖、控制血压等常规治疗;治疗组在常规治疗的基础上使用贝前列腺素钠40μg,口服3次/d,共使用12周。检测早期糖尿病肾病患者治疗前后糖化血红蛋白（ HbA1c）、甘油三酯（TG）、总胆固醇（TC）、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）、24 h尿白蛋白排泄率（24h UAER）、血清胱抑素C（Cys-C）、内生肌酐清除率（Ccr）、血内皮素-1（ET-1）水平,同时利用超声检测肱动脉血流介导的内皮依赖性血管舒张功能（ FMD）。结果两组患者治疗前后血糖、血压、血脂等指标比较差异无统计学意义（ P＞0.05）,治疗组患者治疗后24 h UAER、血清Cys-C、ET-1较对照组显著降低,Ccr、内皮依赖性血管舒张功能（ FMD）较对照组显著升高,差异均有统计学意义（ P均＜0.05）。结论贝前列腺素钠有效地降低早期糖尿病肾病患者的血清Cys-C及24h UAER水平,并改善血管内皮功能。     

Contribution of hyperglycemia and renal damage to urinary C-peptide clearance in non-insulin-dependent diabetic patients.

The variation of urinary C-peptide clearance in relation to hyperglycemia and renal damage was evaluated in 57 patients with non-insulin-dependent diabetes mellitus (NIDDM) with and without overt proteinuria, 14 nondiabetic patients with renal disease (RD) and 18 healthy control subjects. Urinary C-peptide clearance expressed as the ratio of urinary C-peptide to creatinine clearance (CCP/CCR) in the fasting state did not differ in control subjects and RD patients, and was higher equally in NIDDM patients with and without proteinuria. In NIDDM patients without overt proteinuria, urinary levels of C-peptide, beta 2-microglobulin (B2M), N-acetyl-beta-D-glucosaminidase (NAG) and albumin as well as CCP/CCR ratio all decreased significantly with short-term glycemic control (P less than 0.05). Despite a wide range of CCP/CCR ratio (0.07-0.73), a weak but significant correlation (r = 0.56, P less than 0.005) was found between fasting serum and urinary C-peptide levels in NIDDM patients. These results suggest that urinary C-peptide may easily be affected by hyperglycemia per se rather than renal damage, while urinary B2M, NAG and albumin may be affected by both hyperglycemia and renal damage. When the urinary C-peptide level is interpreted, the influence of hyperglycemia on it must be taken into consideration.     

Urinary excretion of glycated albumin in insulin-dependent diabetic patients with normal urinary albumin excretion

Summary Glycation involves both circulating proteins, such as albumin, and structural proteins, such as the components of the glomerular basement membrane. A preferential excretion of glycated albumin (more anionic at physiological pH compared with unmodified plasma albumin) has been reported by some authors, but not by others. We therefore investigated the selectivity index (renal clearance of non-glycated albumin/clearance of glycated albumin) in 25 insulin-dependent diabetic patients with normal urinary albumin excretion and in 19 well-matched control subjects. The selectivity index was significantly higher in diabetic patients than in control subjects: 1.38±0.05 SEMvs 0.98±0.02, p<0.0001. This result is not consistent with a preferential urinary excretion of glycated albumin, at least in normoalbuminuric uncomplicated insulin-dependent diabetic patients.