Proinsulin: metabolic effects in the human forearm.

Five subjects were studied by the forearm perfusion technique with proinsulin at a final plasma conceintration of 1.76 x 10(-9) millimole per milliliter. Two of these subjects were studied with single-component insulin at a concentration of 1.96 x 10(-9) millimole per milliliter. Proinsulin is, in general, biologically less potent than single-component insulin. In contrast to insulin, its effects upon adipose tissue are for the most part greater than upon muscle.

Glucose and lipid homeostasis in the absence of human growth hormone.

To clarify the role of insulin and growth hormone (HGH) in regulating substrate production for body fuel during prolonged starvation, 6 normal subjects and 10 HGH-deficient dwarfs were fasted for 6 days. Four of these dwarfs received HGH during the fast. Blood glucose concentration decreased a mean 15 mg/100 ml in both controls and HGH-treated dwarfs, but decreased 50 mg/100 ml in untreated dwarfs. The final level at which the blood glucose stabilized was significantly higher in the former two groups (65 +/-1.0 mg/100 ml and 88 +/-19 mg/100 ml, respectively, versus 39.0 +/-4.0 mg/100 ml in the untreated dwarfs). The decline in plasma insulin concentration showed a comparable pattern, decreasing from a similar basal level to 7.7 +/-0.4 muU/ml in controls, 8.8 +/-1.1 muU/ml in dwarfs treated with HGH, and to a significantly lower level of 3.8 +/-1.1 muU/ml in untreated dwarfs. When glucose concentrations were plotted against paired insulin values, the correlation in both dwarfs and normals was significant. In normals, no correlation existed at any time between plasma HGH levels and plasma concentration of either glucose or free fatty acid. Free fatty acid, beta-hydroxybutyrate, and acetoacetate increased respectively in normals to peak concentrations in plasma of 1.55 +/-0.11, 2.87 +/-0.23, and 0.77 +/-0.09 mmoles/liter. Untreated dwarfs had significantly greater values of all three (mean maximal concentration: FFA = 2.16 +/-0.17 mmoles/liter, beta-hydroxybutyrate = 4.11 +/-0.34 mmoles/liter, and acetoacetate = 1.16 +/-0.10 mmoles/liter). Values returned toward normal in HGH-treated dwarfs. The cahnges in plasma concentrations of beta-hydroxybutyrate and acetoacetate were not due to changes in renal excretion. In starvation, the relation between insulin on the one hand and glucose and free fatty acid on the other hand is maintained in the absence of HGH. However, the setting of blood glucose concentration at which this relation takes place is decreased in the absence of HGH. This results in a lower than normal insulin level and, consequently, in a higher than normal free fatty acid concentration.

Diabetes mellitus and sexual ateliotic dwarfism: a comparative study.

The incidence of diabetic retinopathy was determined in 38 diabetics and 31 sexual ateliotic dwarfs deficient only in human growth hormone (HGH). The age and sex distribution were approximately the same in each group. The incidence and pattern of glucose intolerance were similar in diabetics and HGH-deficient dwarfs. The majority of diabetics (21 of 38) and HGH-deficient dwarfs (26 of 31) exhibited insulinopenia after glucose, mixed glucose-beef meals, and the infusion of l-arginine. A smaller number of HGH-deficient dwarfs (5 of 31) and diabetics (8 of 38) had normal or augmented absolute insulin responses to these same provocative stimuli. Hypercholesterolemia and hypertriglyceridemia occurred with greater frequency in both diabetics and HGH-deficient dwarfs than in normal controls. 8 of 21 diabetics and 6 of 21 sexual ateliotics exhibited significant hypertriglyceridemia. Five diabetics and six sexual ateliotics had significantly greater than normal serum cholesterol levels. Nearly half of the diabetics (16 of 38) had significant pathological abnormalities of the retina, but these changes were conspicuously absent in HGH-deficient dwarfs. No retinal lesions were detected in any HGH-deficient dwarf.

Capillary basement membrane structure: a comparative study of diabetics and sexual ateliotic dwarfs.

A group of 32 sexual ateliotic dwarfs with an isolated deficiency of human growth hormone (HGH) were shown previously to resemble subjects with genetic diabetes mellitus in terms of hyperlipemia, carbohydrate intolerance, and patterns of insulin secretion. 11 of these dwarfs had needle biopsies of the quadriceps femoris carried out and tissue fixed for electron microscopy. Capillary basement membrane thickness was measured and compared with measurements previously obtained in diabetics and normal controls. Measurements were similar in controls and dwarfs (1080 +/-27 A and 1086 +/-90 A, respectively) and significantly less than in diabetics (2403 +/-119 A). Placed in juxtaposition with the absence of retinopathy in dwarfs and the high incidence in the diabetic group (41%), the data support the thesis that these anatomical abnormalities are largely independent of serum lipid and carbohydrate abnormalities. The data are consistent with a supportive, if not causative role of growth hormone in the pathogenesis of these lesions.

Effects of species of origin, purification levels, and formulation on insulin immunogenicity.

The immunogenicity of purified pork insulins (PPI) with and without (groups 1 and 2, respectively) trace contamination of beef insulin was contrasted with mixed beef pork insulin of lower purity (MBP, group 3) in 137 patients who had not previously been treated with insulin. Patients and physicians were blinded with regard to the species source of insulin and studies were conducted for a minimum of 1 yr. Antibody development to insulin was assessed by species-specific binding of 125I-insulin by acid charcoal extracted sera, as well as by measurement of insulin prebound to immunoglobulins by a polyethylene glycol precipitation method. NPH- and lente-treated individuals had equivalent antibody responses with regard to the rate of development of antibodies, and maximum immune responses to insulin. In all patient groups, antibody bound insulin as well as species-specific binding of 125I-insulin increased significantly over time (all P less than 0.01 for specific binding of pork and beef insulins SBP and SBB, as well as bound insulin). Maximum bound insulin and SBB as well as bound insulin and SBB over the entire course of the study were significantly greater in group 1 than in group 2 patients (both P less than 0.05). The rate of development and magnitude of antibodies' responses in both PPI-treated groups were significantly less than that seen in the MBP group (all P less than 0.01). New formation of antibeef proinsulin antibodies was seen in one patient from groups 1 and 3, but not in group 2. In all groups, insulin dose per day and fasting serum glucose concentrations increased by about 5 U/day and 10 mg/dl over 1 yr, but groups did not differ. MBP insulin used in these studies proved to be significantly less immunogenic than previously available Argentine pure beef insulin, purified by gel filtration. PPI containing even trace contamination of beef insulin was more immunogenic than PPI alone.

Antibodies to covalent aggregates of insulin in blood of insulin-using diabetic patients.

A covalent aggregate twice the size of insulin accounts for approximately 28% of total circulating insulin immunoreactivity in type I diabetic patients. These aggregates are probably covalent dimers of insulin and should contain unique epitopes distinct from the parent molecule. Therapeutic insulin contains a similar material and is the source of the circulating aggregate. Anti-aggregate antibodies were detected by binding-inhibition techniques in 9 of 29 long-term diabetic patients. These antibodies were directed against structures distinct from those of the parent molecule insulin monomer. All antibody-positive patients were men whose blood also contained antibodies to insulin monomer. We conclude that the blood of approximately 30% of insulin-using diabetic patients contains antibodies directed against epitopes unique to the insulin aggregates. Because insulin monomer and aggregates probably share a common primary amino acid sequence, the anti-aggregate antibodies are probably directed against conformational determinants. Further work is needed to determine whether such aggregates promote or accentuate the development of anti-insulin antibodies in certain genetically predisposed individuals.

Quality, efficiency, and cost of a physician-assistant-protocol system for managment of diabetes and hypertension.

Briefly trained physicians assistants using protocols (clinical algorithms) for diabetes, hypertension, and related chronic arteriosclerotic and hypertensive heart disease abstrated information from the medical record and obtained history and physical examination data on every patient-visit to a city hospital chronic disease clinic over a 18-month period. The care rendered by the protocol system was compared with care rendered by a "traditional" system in the same clinic in which physicians delegated few clinical tasks. Increased thoroughness in collecting clinical data in the protocol system led to an increase in the recognition of new pathology. Outcome criteria reflected equivalent quality of care in both groups. Efficiency time-motion studies demonstrated a 20 per cent saving in physician time with the protocol system. Coct estimates, based on the time spent with patients by various providers and on the laboratory-test-ordering patterns, demonstrated equivalent costs of the two systems, given optimal staffing patterns. Laboratory tests were a major element of the cost of patient care,and the clinical yield per unit cost of different tests varied widely.

Presence of insulin autoantibodies as regular feature of nondiabetic repertoire of immunity.

With an ultrasensitive noncompetitive enzyme-linked immunosorbent assay (ELISA), we tested the hypothesis that the presence of insulin autoantibodies in nondiabetic individuals is a normal event. Plasma and peripheral blood mononuclear cells were obtained from 50 nondiabetic whites for determination of insulin autoantibodies by ELISA and radioimmunoassay (anti-insulin IgG [AI-IgG] and 125I-labeled insulin bound [%]), islet cell antibodies, anti-nuclear antibodies and rheumatoid factor, and HLA class II-type antigens (DR, DRw, and DQ). The range of 125I-insulin binding was significantly less than was seen in pretreatment sera from individuals with diabetes (from -0.4 to 0.4% vs. -0.8 to 7.7%, respectively, P = 0.001). Eighty-eight percent of these nondiabetic individuals had significant levels of AI-IgG with preferential binding to human insulin. The geometric mean of AI-IgG concentrations in individuals with significant levels was 180 pM. Binding to human insulin was seen in 88%, to pork insulin in 42%, and to beef insulin in 24% of individuals (P less than 0.001 overall; P less than 0.05 where more bound to pork than beef insulin). Binding of AI-IgG to human insulin-coated plates was substantially inhibited by preincubation with human insulin (median inhibition 57.6%) with little if any inhibition by glucagon, C-peptide, albumin, or IgG. Four individuals had highly specific human AI-IgG as shown by immunoaffinity studies. AI-IgGs were significantly higher in individuals with the HLA haplotype DR4,DRw53,DQ3 and lower in individuals with DR5,DRw52,DQ1 (P = 0.03 for both).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunologic effects of insulin lispro [Lys (B28), Pro (B29) human insulin] in IDDM and NIDDM patients previously treated with insulin.

Insulin lispro [Lys (B28), Pro (B29) human insulin] is a rapidly absorbed analog that has diminished tendency to self-associate. In four open-label, 1-year-long international randomized trials, we contrasted the immunogenicity of insulin lispro versus regular human insulin (RHI) in patients previously treated with insulin who had IDDM or NIDDM. Using a self-blank subtraction assay, we assessed sera for the presence of insulin-specific antibodies (ISA), insulin lispro-specific antibodies (LSA), and cross-reactive antibodies (CRA). Basal insulin needs were provided either with human ultralente (UL) or NPH insulins. After 2 to 4 weeks of therapy with RHI plus UL or RHI plus NPH, 50% of patients were randomly assigned to begin insulin lispro or continue on RHI. At baseline, few pretreated patients had LSA (0-4%) and approximately 10% had ISA, whereas 41-45% of patients with IDDM and 23-27% of patients with NIDDM had CRA (IDDM vs. NIDDM, P < 0.001). Within studies, no significant differences were noted over time in ISA, LSA, or CRA attributable to the type of short-acting insulin. When data were pooled, inconsistent changes were noted in ISA and LSA (LSA were greater in NIDDM vs. IDDM at baseline, P = 0.001, and ISA were greater in IDDM vs. NIDDM at 6 months, P = 0.007). Significant levels of CRA were more common in IDDM at all times (P < 0.001, P = 0.022, and P = 0.002 at baseline, 6 months, and 12 months, respectively). For patients receiving insulin lispro, no significant changes occurred in antibody status among IDDM and NIDDM patients throughout the study (became positive, remained positive, became negative, or remained negative). IDDM patients were more likely to develop or maintain CRA levels (P = 0.008 vs. NIDDM), whereas antibody levels were comparable among positive individuals. No evidence was noted that insulin lispro differs in immunogenicity from RHI in previously treated IDDM and NIDDM patients.

Immunologic aspects of human proinsulin therapy.

We investigated the immunogenicity of human proinsulin (HPI) when used as the sole or principal insulin agonist in insulin-naive patients with insulin-dependent (type I) and non-insulin-dependent (type II) diabetes mellitus. Sixty-one patients (13 type I, 48 type II) were treated with rDNA human insulin (NPH HI with or without regular HI) and 53 were treated with HPI (8 type I, 45 type II). At 6 mo, virtually identical levels of HbA1c (5.2 vs. 5.3%, P = NS) were achieved. However, regular HI was added less often to the treatment regimen in HPI-treated patients (16 vs. 32 patients, P less than .001). Overall, there was no significant increase in proinsulin-specific antibodies in either treatment group. However, 8 of 51 (1 transiently) patients in the HPI group developed low levels of binding of HPI (highest percentage bound was 5%). Two patients in the HI group developed very low levels of HPI binding (1.2 and 1.9%). Binding of HI (greater than 2.4%) was seen in both treatment groups; however, the prevalence of HI binding was less in the HPI group at 6 mo (39 of 60 in HI group vs. 20 of 51 in HPI group, P = .008). Concomitant treatment with regular HI did not affect the prevalence or level of binding of HPI or HI. We conclude that human proinsulin is a weak immunogen when used as the principal insulin agonist and may reduce both the formation of anti-HI antibodies and the need for concomitant therapy with regular HI.

Studies on the relationship between insulin concentrations and insulin action.

The relationship between insulin concentrations and insulin effects was assessed using a 30-min steady-state perfusion of insulin across the human forearm and a 90-min recovery period in 17 normal men. During perfusion, calculated insulin increments in forearm arterial plasma insulin were 87 +/- 4 (group I), 161 +/- 17 (group II), and 333 +/- 55 microU/ml (group III), respectively. Measured venous insulin increments were 33 +/- 4, 66 +/- 6, and 231 +/- 27 microU/ml. During perfusion, venous and arterial increments were linearly related (r = 0.88, P less than 0.001). With discontinuation of perfusion, venous increments of insulin became undetectable after 15 min in groups I and II, and after 30 min in group III. Of the total microunits of insulin perfused, 46.0 +/- 11.0%, 45.3 +/- 9.4%, and 36.5 +/- 4.8%, respectively, remained unaccounted for 90 min after perfusion. Effects of insulin on arteriovenous differences of FFA and potassium persisted throughout the recovery period, with peak effects occurring after perfusion for all groups. Estimated interstitial insulin levels in the three groups fell below 10 microU/ml by 45, 60, and 90 min after perfusion, respectively. Although peripheral tissues had a significant capacity to sequester insulin, the persistence of biologic effects was not consistent with increased concentrations within the interstitial spaces. Effects of insulin upon glucose waned first, followed by effects upon potassium and then lipolysis.

Successful treatment of immune-mediated insulin resistance by human insulin (recombinant DNA).

An 82-yr-old woman with type II diabetes developed antibody-mediated insulin resistance while on mixed pork-beef insulin concomitantly with a non-Hodgkin lymphoma. Insulin resistance was initially treated with highly purified pork insulin, but this was unsuccessful. Treatment with human insulin (recombinant DNA) was associated with marked decrease of both insulin requirement and high-affinity antibodies, increase of free insulin levels, and improvement of diabetic control. This patient's case shows that human insulin can be considered as an alternative treatment for immune-mediated insulin resistance.

Development of IgE antibodies to human (recombinant DNA), porcine, and bovine insulins in diabetic subjects.

Thirty-one previously untreated diabetic individuals received only human insulin (recombinant DNA) for 1 yr with no adverse reactions. The development of serum IgE antibodies to human, porcine, and bovine insulins was assessed by a sepharose radioallergoabsorbent test (RAST). Immunoglobulin (total Ig antibody) binding was assessed by a nonabsorbed species-specific radioimmunoassay. During therapy 2 patients developed IgE antibodies to human insulin as well as increased total Ig binding. The IgE antibodies to human insulin cross-reacted with porcine and bovine insulins, were transient, and were not accompanied by insulin allergy. Ig binding to insulin developed and persisted in 11 of the human insulin-treated diabetics. In comparison, 62 previously untreated diabetic persons received only purified porcine insulin (PPI, less than 5 ppm proinsulin, N = 40) or a mixed bovine-porcine insulin (proinsulin less than 50 ppm, N = 21). Increased Ig antibody developed in 16 of 21 patients receiving mixed bovine-porcine insulin and 25 of 41 PPI-treated patients (P less than 0.05). Seven of 41 PPI-treated patients and 4 of 21 mixed bovine-porcine-treated patients developed anti-insulin IgE antibodies, which were transient in 4 and persisted in 6 diabetic patients. IgE antibody levels did not correlate with total Ig antibody. These data suggest that IgE and total Ig antibodies develop less often after human insulin treatment. Also, the immunoregulation mechanisms responsible for anti-insulin IgE antibody synthesis differ from those regulating other Ig that bind to insulins. Since none of the patients in this study have developed clinical manifestations of insulin allergy or resistance, the clinical relevance of the antibody data must remain speculative.

Metabolic response to oral challenge of hydrogenated starch hydrolysate versus glucose in diabetes.

Our objective was to determine whether 1) hydrogenated starch hydrolysates (HSHs), bulking/sweetening agents used in hard candies, produce a diminished postmeal glycemic response relative to glucose in individuals with and without diabetes and 2) any diminished glycemia is secondary to altered carbohydrate absorption. This study followed a randomized double-blind crossover design and was performed in 12 individuals with diabetes (6 non-insulin dependent, 6 insulin dependent) and 6 nondiabetic individuals. Each group consisted of 3 men and 3 women, none with known neuropathy. After an overnight fast, each subject was challenged with 50 g of glucose, HSH 5875 (7% sorbitol/60% maltitol), and HSH 6075 (14% sorbitol/78% hydrogenated maltooligosaccharides)/1.73 m2 of body surface area in random order on 3 successive days. Individuals with diabetes were maintained on continuous subcutaneous insulin infusion throughout the study to achieve prechallenge glucose levels between 4.5 and 6.7 mM. For all groups, the order of plasma glucose responses over 5 h postchallenge was glucose greater than HSH 6075 greater than HSH 5875, P less than 0.001 (glucose vs. HSH). Pooled data for all groups for areas under the curve confirmed that HSH 6075 resulted in greater glycemia than HSH 5875 (P less than 0.05). This was reflected in the order of C-peptide responses seen in the nondiabetic and non-insulin-dependent groups (glucose greater than HSH 6075 greater than HSH 5875, P less than 0.001). Breath H2 after glucose was low, whereas HSH 5875 greater than HSH 6075 (P = 0.003). Gastric distress was noticed with all products.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological and metabolic responses of patients with history of antibody-induced beef insulin resistance to treatment with beef, pork, human, and sulfated beef insulin.

OBJECTIVE: We evaluated immunological and metabolic responses during therapy with beef (B), pork (P), human (H, rDNA), and sulfated beef (SB) insulins in patients with insulin-antibody-mediated insulin resistance. RESEARCH DESIGN AND METHODS: A randomized double-blind sequential crossover study was performed with each insulin administered for 56 days unless dose reached 200 U/day or allergy developed. Participants were 26 individuals with history of B-P insulin dosage greater than or equal to 200 U/day and insulin binding capacities greater than 0.216 nM (30 mU/ml serum). Twenty-one participants completed the study. Insulin dosage/day, fasting plasma glucose, percentage HbA1, insulin antibody binding capacity (IABC), bound insulin (BI), percentage binding of 125I-labeled B, P, and H insulins, and receptor inhibition factor (RIF) were assessed. RESULTS: Mean insulin dosage (U/day) was significantly greater on B (88.9) than on P (29.2), H (29.4), or SB (29.6). On B, dosage increased in 12 individuals and reached 200 U/day in 6 individuals. Mean fasting plasma glucose (12.1 mM) and HbA1 (11%) were significantly higher on B than on P, H, and SB. Mean IABC, bound insulin, RIF, and percentage of B, P, and H bound were significantly higher on B than on P, H, and SB. Prolonged treatment with SB before entry into the study (greater than 5 wk) resulted in a blunted anamnestic response to B insulin. CONCLUSIONS: Rechallenge with B results in anamnestic immunological response and deterioration of metabolic control. SB, H, and P insulins have equivalent effects in patients with insulin antibody-mediated immunologic resistance.

Mail-in paper strip vs. microcolumn technique for measurement of glycosylated hemoglobin.

We compared glycosylated hemoglobin (GHb) determined from capillary blood samples on paper strips with a standard microcolumn technique in a cross-sectional observational study with laboratories blinded to duplicate samples. Both the standard and the filter strip laboratories were provided with 80 uniquely identified blood samples from 40 individuals. Each laboratory ran duplicate analyses on each sample, yielding 160 GHb values. The within-laboratory correlations between blinded duplicates were 0.98 for the standard (microcolumn technique) and 0.94 for the filter paper (affinity technique) laboratories. The between-laboratory correlations ranged from 0.69 to 0.77. When classifying patients by quartile of glycemic control, the laboratories agreed on 60% of the patients. In an effort to identify sources of between-laboratory variability, varying quantities of blood were applied to strips and reanalyzed. Five microliter drops always yielded inflated estimates of GHb. These data suggest that the estimates of GHb obtained from mail-in paper strips, although internally consistent, differ in important ways from standard laboratory values, reemphasizing the need for caution in the interpretation of interlaboratory and intermethod comparisons.

Use of an automated device for alternative site blood glucose monitoring.

OBJECTIVE: To evaluate the accuracy, comfort, and ease of use of a new automated device for blood glucose monitoring using the arm as an alternative sampling site. RESEARCH DESIGN AND METHODS: These studies use an automated hand-held device that applies a small vacuum, lances the skin, transfers blood onto an electrochemical test strip, and measures glucose. Patients who had type 1 or type 2 diabetes and had received no prior training using this device were recruited from five diabetes clinics. Testing was performed by the patients using this device and by trained healthcare professionals. Blood glucose was measured by 354 patients: from the arm using the device, from the finger using a laboratory reference instrument, and from the finger using the device via the secondary test port. Each patient completed a questionnaire rating the level of pain and ease of use of the device. RESULTS: Blood glucose results in samples obtained from the arm with the automated device agreed well with finger-stick plasma glucose results using a reference instrument (regression slope 0.98, intercept 0.01 mmol/l [0.1 mg/dl], r = 0.96). Error grid analysis showed that 100% of the measurements fell within zones A and B. In the survey, 60% of the patients reported that arm testing with the automated device was "painless;" another 31% of the patients stated that it was "much less painful," and 6% of patients considered using the device "less painful" than finger-stick testing. In a survey containing 15 questions for rating the ease of use with a scale of 1 to 6, the overall mean rating was 5.5. CONCLUSIONS: The automated device is easy to use and provides accurate glucose results; 97% of the patients found it less painful than finger-stick testing.

Short-term effects of a high-fiber, high-carbohydrate diet in very obese diabetic individuals.

The short-term effects of a weight-maintenance diet high in fiber and carbohydrate (HFHC) was studied in seven very obese individuals with type II diabetes mellitus. Such diets contained 68% of kcal as carbohydrate and total fiber content of 81 g (in contrast to 42% and 28 g during baseline). Fasting glucose concentrations, summed glucose concentrations, and 24-h glucosuria were unaffected in six of seven individuals. Fasting insulin levels decreased (-6.0 +/- 2.0 microU/ml, P less than 0.05), but meal-stimulated insulin concentrations were not altered. Triglyceride and HDL cholesterol concentrations were also unaffected. Total cholesterol concentrations fell in four individuals whose initial values exceeded 200 mg/dl. Basal glucose production rates were similar in the obese diabetic subjects, in five nonobese normal subjects, and in one obese normal individual (2.05 +/- 0.19 versus 2.63 +/- 0.30 and 1.85 mg/kg/min for the obese normal individual) while on baseline diets, and did not change with HFHC. During isoglycemic hyperinsulinemic glucose clamp procedures (maintenance of basal glucose concentrations), 40 mU/m2/min was infused intravenously for 2 h. Glucose disappearance rates increased significantly in the normal-weight control subjects, but did not increase during baseline diets in the obese type II diabetic subjects (4.65 +/- 0.80 versus 0.68 +/- 0.40 mg/kg/min). HFHC diet had no effect on glucose disappearance rates. Plasma insulin levels were 131.0 +/- 11.0, 120.0 +/- 11.0, and 120.0 +/- 5.0 microU/ml during these studies. These studies indicate that short-term HFHC diets without caloric restriction were ineffective in improving glycemic control or lessening insulin resistance in very obese patients with type II diabetes.

The plasma glucose response of normal fasting subjects to neutral regular and NPH biosynthetic human and purified pork insulins.

Using doses of 0.1 and 0.15 U/kg, the hypoglycemic activities of neutral regular and NPH biosynthetic human insulin (BHI) and purified pork insulin were compared in normal fasting subjects. Neutral regular insulin was administered by the intravenous and subcutaneous routes and NPH subcutaneously. Comparison of the plasma glucose curves disclosed no statistically significant differences between the maximum effects and the length of time to achieve the maximum effect. Moreover, a dose-response difference between 0.1 and 0.15 U/kg could not established. It is concluded that the hypoglycemic activities of neutral regular and NPH BHI and purified pork insulin are the same.

Immunologic improvement resulting from the transfer of animal insulin-treated diabetic subjects to human insulin (recombinant DNA).

To study the immunologic effects of transfer of patients from animal insulins to human insulin (recombinant DNA), a double-blind comparative trial was begun in over 300 patients. Preliminary results are reported in 116 individuals. After maintenance on purified pork or mixed beef-pork insulins (PPI or MBP) for a minimum of 6 mo, 116 patients were either switched to human insulin or maintained on their previous insulin. Antibody levels were assessed at a baseline visit and then monthly. In PPI-maintained individuals as well as those switched to human insulin there was a significant decrease in qualitative antibody binding as indicated by species-specific binding of 125I beef and human insulins (SBB and SBH), both P less than 0.005. Quantitative binding, as indicated by bound insulin levels, decreased to a much greater extent in patients switched to human insulin, 52% versus 31%, P less than 0.005. Parameters derived from formal antibody titration did not change. In patients maintained on MBP, bound insulin decreased (-36% at 6 mo, P less than 0.002). When switched from MBP to human insulin, there was a marked reduction in all parameters of binding, both qualitative and quantitative: SBP, -68%; SBH, -61%; SBB, -57%; bound insulin, -67% (all P less than 0.001) and decreases in high- and low-affinity binding capacities (P less than 0.02). Thus, for patients treated previously with nonhomologous insulins, transfer to human insulin may result in significant immunologic improvement in anti-insulin antibody levels.