The aim of this study was to investigate the role of plasma glucagon levels on the blood glucose response to intravenous insulin administered continuously or in a pulsatile manner. Six type I diabetic patients proven to have no residual insulin secretion were investigated. Endogenous glucagon secretion was inhibited by a continuous intravenous infusion of somatostatin (100 micrograms/h) and replaced by exogenous infusions of the hormone at three different rates (7.5, 4.5, and 2.5 micrograms/h), resulting in three different plasma glucagon steady-state levels (i.e., approximately equal to 200, approximately equal to 130, and approximately equal to 75 pg/ml, respectively). Each subject, in random order and on different days, was infused intravenously with regular human insulin either continuously (0.17 mU X kg-1 X min-1) or with the same amount of insulin infused in a pulsatile manner (0.85 mU X kg-1 X min-1 during 2 min followed by 8 min during which no insulin was infused). At plasma glucagon levels approximately equal to 200 pg/ml, blood glucose rose from approximately 10 to approximately 13 mM without any difference between the two modalities of insulin infusion. For plasma glucagon levels approximately equal to 130 pg/ml, plasma glucose remained steady throughout the experiments, but during the last 40 min, plasma glucose levels were significantly lower when insulin was administered intermittently. This greater blood glucose-lowering effect of pulsatile insulin occurred earlier and was more pronounced for plasma glucagon levels averaging 75 pg/ml. We conclude that the greater hypoglycemic effect of insulin administered intravenously in a pulsatile manner in type I diabetics critically depends on plasma glucagon circulating levels.

Forty-five insulin-dependent diabetics were randomized to 1 yr treatment with either continuous subcutaneous insulin infusion (CSII), multiple insulin injections (MI), or continued conventional treatment. The CSII group used regular insulin only, the MI group used 4-6 premeal injections of regular insulin and intermediate insulin at night, and the conventional group used two daily injections of combined regular and intermediate insulin. Only highly purified porcine insulin was used. Near normoglycemia was obtained during CSII and MI but not during conventional treatment. Antibodies against insulin were measured in serum samples by measuring the binding of iodinated porcine insulin to serum after removal of free and antibody-bound insulin from the samples by acid charcoal. The percent binding of 125I-labeled insulin increased significantly during MI and CSII, in contrast to conventional treatment. Nineteen patients had sufficient binding capacity for Scatchard analysis. In the CSII and MI groups, high- or low-affinity antibodies or both were induced. When insulin was administered subcutaneously during MI or CSII for 1 yr, the insulin antibody production increased, in contrast with conventional treatment.

We studied the renal effects of nicardipine, a calcium entry blocker, in eight patients with essential hypertension (group A, WHO I or II), six hypertensive type II diabetics with mild-to-moderate nephropathy (group B, urinary albumin 200-789 mg/day), and six hypertensive type II diabetics with severe or advanced nephropathy (group C, urinary albumin 1,596-4,300 mg/day). The patients received an intravenous dose of nicardipine hydrochloride (0.5 mg) or saline placebo in a random order. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by means of thiosulfate sodium and p-aminohippurate, respectively, during the 30 min after the nicardipine or saline injection. Blood pressures were serially monitored during the study. Nicardipine reduced both systolic and diastolic blood pressures significantly (P less than .05 to .01) at all measurement periods in all study groups compared with the respective placebo. Nicardipine increased RBF (P less than .01), GFR (P less than .05), and urinary Na+ excretion (P less than .01) and decreased total renal vascular resistance (P less than .01) in groups A and B, but these parameters remain unchanged in group C. The filtration fraction remained unaltered in all groups. The results indicate that nicardipine has several favorable renal effects with a concomitant hypotensive action in hypertensive type II diabetics with mild-to-moderate nephropathy, as observed in patients with uncomplicated essential hypertension, and the renal pharmacological responsiveness appears to be related to the severity of nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

To study the effect of sorbinil on the alteration of the blood-retinal barrier, 32 adult-onset, non-insulin-dependent diabetic patients with minimal or no retinopathy were randomly assigned to receive either oral sorbinil (250 mg once a day) or a placebo for 6 mo. All patients underwent fundus photography, fluorescein angiography, and vitreous fluorophotometry before treatment and at 3 and 6 mo after treatment. Vitreous fluorophotometry data showed that the alteration of the blood-retinal barrier increased significantly less in the sorbinil-treated group compared with the placebo group during the 6-mo study period. Side effects were limited to hypersensitivity reactions, with skin rash and fever, in only 2 of the 16 patients who received the drug. These hypersensitivity reactions disappeared with discontinuation of the medication. Aldose-reductase inhibition may play an important role in stabilization of the blood-retinal barrier in early diabetic retinopathy.

The Diabetes Control and Complications Trial (DCCT) is a randomized, controlled clinical trial designed to assess the relationship between glycemic control and the development, progression, or amelioration of early vascular complications in persons with insulin-dependent diabetes mellitus (IDDM). The DCCT consists of two parallel studies: a primary prevention study and a secondary intervention study. The principal outcome in the primary prevention study is the initial appearance and subsequent progression of background retinopathy. In the secondary intervention study, the principal outcome is the progression or amelioration of preexistent minimal retinopathy. Subjects are randomly assigned to receive either experimental or standard therapy. Experimental therapy involves the use of an intensive insulin regimen designed to maintain near-normal glycemic levels in the absence of severe hypoglycemia. Standard treatment is designed to maintain near-normal glycemic levels in the absence of severe hypoglycemia. Standard treatment is designed to maintain subjects free of clinical symptoms related to hyper- or hypoglycemia while receiving up to two insulin injections daily. Two hundred seventy-eight volunteers have been enrolled in 21 centers in the United States and Canada in a preliminary study to assess the feasibility of conducting a full-scale, long-term clinical trial. Based on an external review of the feasibility study results, the DCCT will be expanded to include over 1400 subjects treated for a period of up to 10 yr. This article describes the DCCT and the considerations that led to the choice of specific design features for the feasibility phase.

Thirty patients with insulin-dependent diabetes mellitus (IDDM) who had advanced background retinopathy were randomized to unchanged conventional treatment (UCT) or to continuous subcutaneous insulin infusion (CSII). They were followed prospectively for 2 yr. The mean blood glucose and hemoglobin A1C (HbA1C) were significantly lower in the CSII group than in the UCT group. The mean blood glucose and HbA1C did not change from the first to the second year in either of the treatment groups in spite of less frequent home-monitoring of blood glucose and less frequent outpatient visits during the second year. Four patients in the CSII group and five in the UCT group developed proliferative retinopathy. However, a marginally significant trend was found toward more frequent improvement of retinal morphology in the CSII group (47%) than in the UCT group (13%). Beat-to-beat variation was found to deteriorate significantly with UCT compared with a nonsignificant improvement with CSII therapy. Vibration sense was unchanged in both treatment groups. It is concluded that near-normal blood glucose levels can be maintained with CSII therapy in spite of less frequent home-monitoring of blood glucose and outpatient visits. Furthermore, established background retinopathy may progress to proliferative retinopathy in spite of 2 yr of near-normal blood glucose levels. However, a marginally significant trend toward more frequent improvement of retinal morphology was found among CSII-treated patients compared with conventionally treated patients. Large-scale, prospective, randomized studies are needed to confirm these results.

As part of a multicenter trial, 70 individuals with insulin-dependent diabetes were randomized to either conventional insulin therapy (CIT) or continuous subcutaneous insulin infusion (CSII). In order to standardize patient selection in the six participating centers, one of the eligibility criteria was the demonstration that each patient had no residual endogenous insulin secretion as assessed by plasma C-peptide determinations. The patients were of average (+/- SEM) age of 33.0 +/- 1.6 yr, had had diabetes for a mean (+/- SEM) duration of 17.4 +/- 1.1 yr, and had both fasting and postglucagon stimulation C-peptide values of less than 0.1 pmol/ml, consistent with clinically insignificant endogenous insulin secretion. There was no change in C-peptide response at 4 or 8 mo compared with baseline values, whether or not the patient's glucose control remained unchanged (CIT group) or significantly improved to near-normoglycemia (CSII group). In a subgroup of 34 patients at three centers, the 24-h mean glucose concentration was significantly lower in the CSII group compared with the CIT group at 4 mo (126 +/- 10 versus 176 +/- 14 mg/dl) and at 8 mo (121 +/- 5 versus 183 +/- 15 mg/dl) (P less than 0.005). Although the 24-h mean serum free immunoreactive insulin levels were shown to be no different at baseline (27.4 +/- 3.8 versus 26.2 +/- 3.1 microU/ml) or after 4 mo (22.5 +/- 3.2 versus 25.6 +/- 3.2) or 8 mo (26.5 +/- 3.4 versus 28.8 +/- 3.4) of CIT or CSII therapy, respectively, the mean increase of free insulin concentrations in relation to the main meals was greater in the CSII group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The general and ophthalmologic eligibility criteria were applied in the course of formal screening of selected members of clinic populations at the six treatment centers between August 1980 and November 1981. Patients eligible on the grounds of the history and general physical examination underwent a detailed ophthalmologic examination and determination of C-peptide status. Initial rates of recruitment were slow, which occasioned modifications of the eligibility criteria and a prolongation of the recruitment phase. All six clinics approached their goal of at least six patients in each of the continuous subcutaneous insulin infusion (CSII) and conventional insulin treatment (CIT) groups, with a final total of 70 randomized subjects. The method of paired randomization was acceptable, but led to some delay during periods of slow recruitment activity. Data from two patients who chose to drop out of the study shortly after randomization are included in the baseline characteristics. There was no difference between treatment groups with respect to age or duration of known diabetes, body weight, systolic blood pressure, proportion of cigarette smokers, retinopathy level as assigned by analysis of stereofundus photographs, or microaneurysm counts performed on fluorescein angiograms. A trend toward milder retinopathy in the CIT group proved to be statistically insignificant. Subsequent assessment of stereofundus photographs at the Fundus Photograph Reading Center indicated that six patients were misclassified by treatment center ophthalmologists with respect to ophthalmologic eligibility. We conclude that recruitment goals were met and randomization was successful.

Data from 70 type I diabetic patients with nonproliferative retinopathy participating in a multicenter clinical trial of control and complications were analyzed to test for associations of clinical variables with baseline levels and 8-mo changes in retinopathy. Predictor variables included age, duration of diabetes, systolic blood pressure, inpatient and outpatient plasma glucose levels, glycosylated hemoglobin (HbA1), M-values, serum cholesterol, serum triglycerides, and creatinine clearance. Retinopathy was assessed by fundus photography and graded at the Fundus Photograph Reading Center according to a detailed protocol. For the entire group, baseline retinopathy was positively correlated (P less than 0.05) with baseline systolic blood pressure, plasma glucose, HbA1, serum cholesterol, and duration of disease and negatively correlated with creatinine clearance. Conversely, during treatment, progression of retinopathy was negatively correlated (P less than 0.05) with mean levels during treatment of plasma glucose, HbA1, M-values, serum cholesterol, and with changes during treatment in plasma glucose and serum triglycerides. Two-group and three-group multivariate classification analysis of progression of retinopathy (improved or unchanged versus worsening--mild or moderate) indicated lower plasma glucose as the single best predictor of worsening of retinopathy (P less than 0.05), correctly classifying 71% of patients with positive progression. Decreased creatinine clearance during therapy was found to be the best discriminator between mild and moderate progression. Other multivariate models yielded specificity values of up to 71% and sensitivity values of up to 92%. We conclude that associations among clinical predictors and retinopathy during short-term glycemic control differ strikingly from those at baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Sixty-five patients with mild to moderate nonproliferative diabetic retinopathy who enrolled in a prospective controlled clinical trial had stereofundus photographs assessed for change over an 8-mo period. The entire study group showed a worsening of retinopathy with time (P less than 0.001). The worsening was greater in the pump-treated group (15/32) than in the conventionally treated group (9/33). The significance of this difference ranged from P = 0.67, if changes in mean retinopathy level for each patient were compared, to P = 0.177 if a grading system keyed to the worse eye was compared. The difference in rates of change between treatment groups was found to be related to the baseline mean retinopathy level (P = 0.031), but less significantly so if baseline retinopathy keyed to the worse eye was used as a covariate (P = 0.08). Worsening occurred more frequently in those patients starting with the lower retinopathy levels. Progression was associated with the appearance of retinal infarcts (cotton-wool spots, soft exudates) and/or intraretinal microvascular abnormalities, with the pump patients showing a significant increase in these individual retinal lesions compared with the conventionally treated patients over 8 mo (P less than 0.025).

As part of a randomized, prospective trial in subjects with insulin-dependent diabetes assigned to either continuous subcutaneous insulin infusion (CSII) or to their unchanged conventional insulin treatment (CIT) for 8 mo, patients completed questionnaires dealing with general responses and clinical and technological problems. Although there was no significant difference between treatment groups with respect to the number of patients experiencing severe hypoglycemia (i.e., requiring intravenous glucose or intramuscular glucagon injection), there were nine episodes in six patients during CSII compared with one episode during CIT. Diabetic ketoacidosis occurred significantly more often in the CSII group (nine episodes in eight patients) than in the CIT group (no episodes). A number of CSII-related failures occurred, including omission of premeal bolus, needle dislodgement, pump accidentally turned off, and leakage at the infusion site. At 8 mo, 85% of CSII-treated patients wished to continue indefinitely on the pump, and almost all would continue with self-monitoring of blood glucose even if they stopped CSII.

Determination of glycemic differences between groups treated with continuous subcutaneous insulin infusion (CSII) or conventional insulin therapy (CIT) was central to the major objective of the study. Assessment of glycemia was based on 24-h inhospital profiles of plasma glucose; pre- and postprandial and bedtime (seven time points) diurnal profiles performed monthly on outpatient samples; and glycosylated hemoglobin (HbA1) measured bimonthly at each center. The correlation between plasma glucose determinations in the central laboratory and in local laboratories was 0.988. Significance of differences between treatments was by analysis of variance and least-squares regression. At baseline, mean inhospital plasma glucose and HbA1 concentrations and insulin dosages were identical in the groups randomized to CSII or CIT. A prompt decrement of indices of glycemic control during CSII was observed such that mean decrements sustained over the 8-mo treatment period in home and in hospital plasma glucose profiles and HbA1 relative to values obtained during CIT (P less than 0.0001). The likelihood of CSII-treated patients achieving glycemic indices within the normal range was increased. The standardization of the mean and the M-value calculated from inhospital glucose profiles during CSII and CIT at 4 and 8 mo indicated that there was less plasma glucose fluctuation during CSII. The method of pooling standardized local HbA1 measurements from the six centers appeared to be an adequate substitute for centrally performed HbA1 determinations. Advantages of inhospital plasma glucose measurements in terms of accuracy and ability to obtain nocturnal samples contrasted with the likelihood of increased realism and superior correlation with HbA1 in home-obtained samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Newly presenting maturity-onset diabetic subjects were put on diet and if, after 3-4 mo, their fasting plasma glucose continued greater than 6 mmol/L, they were randomized to three therapies: (1) continuing diet alone, (2) with additional sulfonylurea, or (3) with additional basal insulin supplement provided by ultralente insulin. Obese patients were also randomized to metformin therapy. The aim was to lower the fasting plasma glucose to less than 6 mmol/L and the degree to which this reduced the hemoglobin A1C (HbA1C) concentration was studied in 195 patients over 1 yr. Sulfonylurea and insulin similarly reduced (P less than 0.001) the fasting plasma glucose from 8.3 +/- 1.9 to 6.7 +/- 1.3 mmol/L (mean +/- 1 SD) and 8.6 +/- 2.2 to 6.8 +/- 1.4 mmol/L, respectively. This was accompanied by a significant reduction (P less than 0.001) of the HbA1C to the high normal range, from 9.1 +/- 2.1% to 7.8 +/- 1.2%, and from 9.1 +/- 1.9% to 8.1 +/- 1.3%, respectively, both values at 1 yr being significantly (P less than 0.05) lower than in patients randomized to diet alone. Patients randomized to diet alone had little change in fasting plasma glucose (8.6 +/- 1.8 to 9.3 +/- 2.3 mmol/L) or HbA1C (8.8 +/- 1.7% to 9.1 +/- 1.6%, respectively). Thus, the simple therapeutic aim of trying to reduce the fasting plasma glucose to less than 6 mmol/L is an effective means of reducing the HbA1C to a high-normal level. The HbA1C and fasting plasma glucose concentrations were similarly related for all three therapies (HbA1C [%] = 0.47 X fasting plasma glucose [mmol/L] + 4.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Two-hundred and two pregnant women with impaired glucose tolerance were randomized to treatment with diet or diet and insulin by stratified selection. Self-monitoring of blood glucose was performed six times a day, 3 days/wk. Dietary treatment was considered inappropriate if fasting and postprandial blood glucose values exceeded 7 and 9 mmol/L, respectively, in which case insulin therapy was instituted. Insulin doses were adjusted according to blood glucose values, aiming at fasting and postprandial values below 5 and 6.5 mmol/L, respectively. There were no perinatal deaths. The two treatment regimens disclosed no differences regarding achieved degree of maternal blood glucose control, hemoglobin A1c at delivery, obstetric or neonatal complications, infant's size at birth including skin-fold thickness, or C-peptide concentration in cord serum. Routine treatment of pregnant women with mild carbohydrate intolerance with insulin seems unnecessary. However, 15 patients (14%) in the diet group needed insulin to achieve acceptable blood glucose control, underlining the importance of monitoring blood glucose to detect those who are at risk of developing overt diabetes.

In the present study, 12 patients with non-insulin-dependent diabetes mellitus (NIDDM) consumed eucaloric, mixed food diets on three consecutive days. Diets provided 50% of the calories as carbohydrate, 35% as fat, and 15% as protein. The percent of carbohydrate fed as complex (starches) and simple (mono- and disaccharides) varied among the 3 days. On day 1, the diet contained 80% of the carbohydrate as complex and 20% as simple (80/20); another contained 50% complex and 50% simple (50/50); and the final diet contained 20% of the carbohydrate as complex and 80% as simple (20/80). All simple carbohydrates represent naturally occurring sugars in fruits, vegetables, and dairy products. No refined sugars were added to any of the diets. The three experimental diets were randomly assigned using a 3 X 3 Latin square design. Blood was obtained hourly from 0800 to 1700 h for day-long glucose and insulin concentrations, and 24-h urine collections were made for the measurement of urine glucose. Mean (+/- SEM) day-long glucose concentrations were significantly greater for the 80/20 diet (2245 +/- 199 mg/dl X h, P less than 0.05) than for either the 50/50 (2030 +/- 157 mg/dl X h) or the 20/80 diets (2008 +/- 160 mg/dl X h). No significant differences were noted between the 50/50 and the 20/80 diets. In contrast, day-long insulin concentrations were not significantly different with 401 +/- 62, 370 +/- 50, and 369 +/- 60 mu U/ml X h on the 80/20, 50/50, and 20/80 diets, respectively. Twenty-four-hour urinary glucose excretion paralleled plasma glucose concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Seven normal volunteers were studied on two different occasions during which 4-h pulsatile (PULS: 0.8 mU X kg-1 X min-1, 7.5 min of 15) and continuous (CONT: 0.4 mU X kg-1 X min-1) intravenous (i.v.) infusions of human insulin (Actrapid HM, Novo) were randomly compared. A euglycemic glucose clamp was performed and a 3-3H-glucose infusion was used for determination of endogenous glucose production (EGP) and metabolic clearance rate (MCR) of glucose. Plasma glucose was similar in both conditions; plasma insulin was stable at about 29 mU/L (CONT) and fluctuated between 10 and 45 mU/L (mean: 28, PULS). Exogenous glucose infused was 1.137 +/- 0.058 and 1.088 +/- 0.099 g X kg-1 X 4 h-1 in CONT and PULS, respectively (NS). EGP was totally suppressed in both conditions. Glucose MCR increased similarly to a maximum of 6.71 +/- 0.19 (CONT) and 6.79 +/- 0.59 (PULS) ml X kg-1 X min-1 during the fourth hour. C-peptide plasma levels remained stable, whereas plasma glucagon, free fatty acids, and 3-hydroxybutyrate were similarly suppressed in both tests. Thus, under these conditions, pulsatile and continuous insulin infusions have similar metabolic effects. These data contrast with those of Matthews et al. (1983) who reported that, at lower plasma concentrations (5-19 mU/L), pulsatile insulin had greater hypoglycemic effect than did continuous delivery. It is concluded that pulsatile insulin shows no greater activity under normoglycemic, moderately hyperinsulinemic conditions in man.

The impact on remission of normalizing blood glucose levels immediately after diagnosis of type I diabetes was studied in 14 adolescents. Accordingly, in this randomized prospective primary intervention study, 7 of the subjects (i.v. group) received insulin by continuous intravenous (i.v.) infusion via a portable preprogrammed system for 28-62 days and 7 (s.c. group) received conventional subcutaneous (s.c.) therapy. Before therapy, the two groups did not differ significantly with respect to glycosylated hemoglobin, fasting plasma C-peptide, or 24-h urinary C-peptide excretion. During the infusion period, the overall mean fasting plasma glucose (FPG) concentration for the i.v. group was 84 mg/dl with a mean coefficient of variation of 18 +/- 4% (mean +/- SD). During the comparable period for the s.c. group, the mean FPG was 253 mg/dl with a coefficient of variation of 30 +/- 20%. Twenty-four-hour urinary glucose excretions for the two groups were 0.29 +/- 0.06 (mean +/- SEM) and 59 +/- 11 g/day, respectively. Daily insulin requirements in the i.v. group decreased from 1.47 +/- 0.19 U/kg body wt/day at the start to 0.47 +/- 0.10 U/kg/day at the end of the infusion period. Notably, 10-25 days after the infusion period, 5 of 7 subjects experienced a further decrease to a low of 0.27 +/- 0.01 U/kg/day. The mean peak and low requirements in the s.c. group were 0.71 +/- 0.15 and 0.33 +/- 0.13 U/kg/day, respectively, with the only peak requirements being significantly different (P less than 0.01). No patient was able to discontinue insulin therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

The final results of a randomized controlled clinical trial of photocoagulation for diabetic maculopathy are reported, when all patients have been followed for at least 5 yr and some for as long as 7 yr. Ninety-nine patients with two similarly affected eyes had one eye chosen by a random procedure, treated with the xenon-arc photocoagulator; the untreated eyes remained as control. The mean visual acuity deteriorated by less than one line in treated eyes but by more than 2 lines in the controls (P less than 0.01). The difference in deterioration was greatest in patients whose initial vision was 6/6-6/9, and was not significant in those whose visual acuity was 6/36 or worse. Thirteen patients became blind in both eyes (visual acuity of 6/60 or less for 2 consecutive yearly assessments), 6 in the treated eye only, and 26 in the control eye only (P less than 0.01). Again the divergence between treated and control eyes was most marked in those whose initial vision was 6/6-6/9, (only one treated but 10 control eyes became blind). Hard exudates, microaneurysms, and hemorrhages improved more in the treated eyes (0.05 less than P less than 0.001) and more control eyes developed new vessels during the follow-up period. Twenty-three patients died during follow-up and another 16 failed to complete the study. Though the blood pressure of those who died was higher than those who survived (P less than 0.05 for both systolic and diastolic) no other medical abnormalities at entry had any clear effect on visual outcome or 5-yr survival. It is concluded that photocoagulation is of benefit in maintaining vision in diabetic maculopathy if the disease is not too far advanced.

A double-blind, randomized, placebo-controlled cross-over trial of the aldose reductase inhibitor sorbinil was undertaken in 15 patients (age 35-68 yr) with chronic painful diabetic neuropathy. Treatment was evaluated by subjective pain responses, clinical examination, vibration perception threshold, motor and sensory nerve electrophysiology, and cardiovascular reflex tests of autonomic nerve function. Among the many measurements, only pain, tendon reflex scores, and sural sensory potential amplitude improved significantly during sorbinil administration, while scores of clinical sensory examination deteriorated. Four patients experienced an idiosyncratic reaction that rapidly recovered on discontinuing the drug. This study suggests that aldose reductase inhibitor treatment with suggests that aldose reductase inhibitor treatment with sorbinil may have an effect on symptomatic diabetic neuropathy in man.

Cyclosporin A (CsA) is a unique immunosuppressive cyclic polypeptide that is currently being used, either alone or in combination with low-dose prednisone, to treat recipients of renal or pancreas allografts in clinical trials. CsA is very effective in preventing rejection of heart and renal allografts in rodents, but in nontoxic doses does not consistently prevent rejection of pancreas and islet allografts. Therefore, we tested low-dose CsA in various combinations with low-dose prednisone, azathioprine, or total lymphoid irradiation in rat heart, pancreas, and islet allograft models. Several combinations are synergistic and when administered continuously can indefinitely prevent rejection of heart allografts, but only delay rejection of pancreatic allografts, transplanted across a major histocompatibility barrier, CsA by itself prolonged the survival of islet allografts transplanted across a minor, but not a major, histocompatibility barrier. CsA and azathioprine had a synergistic effect in the minor histocompatibility barrier islet transplant model, but, in the nontoxic combinations tested, could not prevent rejection indefinitely. A randomized prospective trial comparing standard immunosuppressive therapy (ALG, prednisone, and azathioprine), with CsA and low-dose prednisone for clinical renal allotransplantation is ongoing at the University of Minnesota. Current actuarial 1-yr graft survival is 93% for CsA-treated patients (N = 48) and 81% for conventionally treated patients (N = 52). Patient survival is 98% for CsA and 100% for conventionally treated patients. A pilot trial of CsA in the clinical pancreas transplant program at the University of Minnesota is also underway. Since 1978, 46 pancreas transplants have been performed in 43 patients. Of 30 technically successful pancreatic allografts, 5 of 12 recipients treated with conventional immunosuppression and 6 of 18 recipients treated with CsA currently have functioning grafts and are insulin independent between 1 and 44 months after transplantation. The results of metabolic studies are similar in conventional and CsA-treated patients with functioning pancreas grafts. Since pancreas grafts may fail for reasons other than rejection, further observations are needed to ascertain the role of CsA in clinical pancreas transplantation.