272 Horm. metabol. Res. 15 (1983) K.J. Schliiter, F. Enzmann and L. Kerp
chemistry, ECG, physical examination and oral glucose tolerance
tests (100 g) were normal.
In a randomized study, each subject received both Biosynthetic
Human Insulin (BHI) (Eli Lilly, Indianapolis, CT 4969-1B) and
identical formulated purified pork insulin (PPI) (Eli Lilly, Indiana-
polis, CT 4970-OA) intravenously (bolus: 0.1 U/kg BW). The com-
pound of BHI used in this experiment was identical to the BHI (Lot
615-70N-174-9) used in the USP-rabbit hypoglycemia assay. The
biological activity in rabbits was 27.5 ±1.7 units/mg, which was
160 nmoles/mg for BHI and 159 nmoles/mg for PPI.
The tests were performed at one week intervals in this study. One
hour before the administration of insulin, three catheters were in-
serted into antecubital veins. The glucose-controlled insulin infusion
system (Biostator, Life Science Instruments, Miinchen, FRG) was
calibrated for continuous blood glucose monitoring and glucose in-
fusion. The plasma glucose concentration was clamped at individual
fasting baseline levels (± 0.25 mMol/1). The Biostator was pro-
grammed to maintain the individual (76—96 mg/dl) euglycemia of
the subjects. Glucose (40 g/100 ml) was infused through the three
channels (saline-, glucose-, and optional channel) of the Biostator.
The maximum glucose infusion by the Biostator was 2.4 g/min.
After an hour's rest, a bolus of insulin (0.1 U/kg BW) was injected
intravenously. Venous blood samples were obtained at-15, 0, 10,
15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 75, 90, 105 and
Plasma glucose was determined by the glucose oxidase technique with
a Beckmann glucose analyzer (Beckmann Instruments, Inc., Fullerton,
The following radioimmunoassays were carried out: serum insulin
(Phadebas-Insulintest, Pharmacia-Diagnostics, AB, Uppsala, Sweden)
(the cross-reaction of PPI and BHI with the antibody used in this
RIA was identical in the range from 10 MU/ml to 320 MU/ml), serum
Fig. 1 Plasma glucose (mg/ml), serum insulin (MU/ml), serum
C-peptide (Riamat, C-peptide assay, Byk-Mallinckrodt, Diezenbach,
C-peptide (ng/ml) after an i.v. bolus (0.1 U/kg BW, given at 0
FRG), serum Cortisol (Cortisol-Ria, Travenol, Cambridge, Mass.),
minutes) of Biosynthetic Human Insulin (• •) and purified
and serum growth hormone (Serono, Freiburg, FRG).
pork insulin (o—o) during euglycemic clamp in eight male
Interassay variations were reduced by using the same immunoassay volunteers. The values at each time interval represent the mean
for all samples of an individual subject. Intra-assay error, measured ± SEM of eight samples. There was no statistical significance of
as coefficient of variation, was below 5% in all cases. differences between the porcine and human group.
The data are expressed as mean ± SEM. Areas under the concentra-
tion-time curves were calculated according to the equation:
*f ( x n+l- x n> (vn+l + yn)
Wilcoxons test for paired differences was used.
Eight male volunteers received either Biosynthetic Human
Insulin (BHI) (0.1 U/kg BW) or purified porcine insulin
(PPI) during an euglycemic clamp study. Plasma glucose,
serum insulin, serum C-peptide, serum growth hormone,
and serum Cortisol concentrations obtained from the
venous blood samples are shown in Fig. 1 and Fig. 2.
The individual fasting plasma glucose values (BHI: 89.1 ±
1.6 mg/dl;PPI: 90.1 ± 2.7 mg/dl) were maintained through-
out the clamping procedure, but those following Bio-
synthetic Human Insulin were slightly lower than those
following purified porcine insulin. Throughout the experi-
ment the maximum blood glucose fluctuation was 20 mg/dl
and the coefficient of variation of the plasma glucose values Fig. 2 Serum growth hormone and serum Cortisol after an i.v.
was below 15%. bolus (0.1 U/kg BW, given at 0 minutes) of Biosynthetic Human
Insulin (• • ) and purified porcine insulin (o—o) during
Serum insulin concentrations did not differ during the test euglycemic clamp in eight male volunteers. The values at each time
period. Following the intravenous administration identical interval represent the mean ± SEM of eight samples.
X, values that differ significantly from the human insulin group at
peak values (BHI: 309.3 ± 61.0 juU/ml; PPI: 335.2 ± 64.2 that time interval (p< 0.05 by paired Wilcoxon's test).
/xU/ml) of insulin were obtained.
Potencies of Biosynthetic Human and Purified Porcine Insulin Horm. metabol. Res. 15 (1983) 273
Serum C-peptide levels following Biosynthetic Human Chiasson, Keller and Rubenstein 1978; Beischer, Schmid,
Insulin and purified porcine insulin did not differ signifi- Kerner, Keller and Pfeiffer 1978) may be due to this tech-
cantly. A suppression of endogenous insulin secretion by nical difference.
exogenous insulin was not observed (Fig. 1). A significant A small but significant rise in serum growth hormone and
(p< 0.05) elevation of serum growth hormone concentra- serum Cortisol concentrations was observed following the
tion (from 2.8 ± 1.7 ng/ml at 0 minutes to 12.1 ± 6.2 ng/ml injection of a bolus of purified porcine insulin, which was
at 30 minutes) occurred after the administration of puri- not observed after Biosynthetic Human Insulin. This can-
fied porcine insulin. BHI did not produce any fluctuation not be attributed to differences in plasma glucose or to
of serum growth hormone (2.5 ± 1.9 ng/ml at 0 minutes plasma glucose concentrations because plasma glucose was
and 2.5 ± 2.0 ng/ml at 30 minutes). clamped at individual fasting glucose levels. The secretion
Serum Cortisol levels were also elevated (A serum Cortisol of growth hormone and of Cortisol appears to be a response
38.8 ± 8.1 ng/ml) after purified porcine insulin but not to the heterologous insulin.
after human insulin (A serum Cortisol 23.1 ± 4.5 ng/ml) Significantly more exogenous glucose was required to
(p<0.05). compensate the hypoglycemic effect of Biosynthetic Human
The amount of glucose required to compensate the effect Insulin in comparison to purified pork insulin (+ 30.6 ± 7.6
of exogenous insulin was significantly (2p< 0.007) higher percent). In five insulin-dependent diabetic subjects BHI
after Biosynthetic Human Insulin (63.5 ± 4.5 g/2h) than was more (but not significantly) effective than natural pork
after purified porcine insulin (50.4 ±5.2 g/2h). insulin (Klier, Kerner, Torres and Pfeiffer 1981). This dif-
Table 1 shows the individual glucose requirements over the ference which is in contrast to a previous study (Massi-
two-hour periods for each subject. Benedetti, Burrin, Capaldo and Alberti 1981) with the
insulin infusion technique, can be explained by the small in-
crements of endogenous Cortisol and growth hormone ob-
served after porcine insulin. Cortisol and growth hormone
produced hyperglycemia by decreasing both hepatic and
extrahepatic sensitivity to insulin (Rizza, Mandarino and
The glucose clamp technique has been used to assess the Gerich 1981; Rizza, Mandarino, Westland and Gerich
biological activity of insulin by continuous infusion (De 1981).
Fronzo, Tobin and Andres 919;Pfeiffer, Thum and
Clemens 1974;Nasadini, Noy, Kurtz and Alberti 1981; On the other hand a significantly inhibited hepatic glucose
Massi-Benedetti, Burrin, Capaldo and Alberti 1981). In this production has been observed after porcine insulin in com-
study, however, a bolus injection of insulin was used. The parison to semisynthetic human insulin (Mutter, Keller and
peak serum insulin concentrations (about 300 /iU/ml in Berger 1982). The weaker suppression of hepatic glucose
comparison to values obtained by continuous infusion of production following porcine insulin, caused by Cortisol
about 50—100 ^U/ml) (Massi-Benedetti, Burrin, Capaldo and growth hormone secretion, might explain the comparab-
and Alberti 19Sl;Dobeme, Schulz and Reaven 1981) per- ly low glucose requirement following porcine insulin in-
sisted for only a short period while continuous infusion jection in comparison to human insulin. The results indi-
results in prolonged elevated levels. The fact that we have cate that homologous insulin produces effects which are
not observed a suppression of endogenous insulin secretion different from those produced by heterologous insulin in
as judged by serum C-peptide (Liljenquist, Horwitz, Jennings, man.
Table 1 Glucose requirement (g/2h) after a bolus injection (0.1 U/kg
The authors gratefully acknowledge the skilled technical assistance
BW) of Biosynthetic Human Insulin (BHI) and purified pork insulin
of Mrs. Heike Vorwerck and thank Prof. Dr. John A. Galloway
(PPI) during euglycemic clamp.
(University of Indianapolis) for his comments on the manuscript.
Subject BHI PPI References
No. Beischer, W., M. Schmid, W. Kerner, L. Keller, E.F. Pfeiffer: Does
insulin play a role in the regulation of its own secretion? Horm.
Metab. Res. 10: 168-169 (1978)
De Fronzo, R.A., J.D. Tobin, R. Andres: Glucose clamp technique:
a method for quantifying insulin secretion and resistance. Am.
J. Physiol. 237 (3): E214-E223 (1979)
Doberne, L., M.S. Greenfield, B. Schulz, M. Reaven: Enhanced
glucose utilization during prolonged glucose clamp studies.
Diabetes 30: 829-835 (1981)
Klier, M., W. Kerner, A.A. Torres, E.F. Pfeiffer: Comparison of the
biologic activity of Biosynthetic Human Insulin and natural
pork insulin in juvenile-onset diabetic subjects assessed by the
glucose controlled insulin infusion system. Diabetes Care 4:
*Significance of mean differences, p< 0.007. 193-195 (1981)