Diabetes, Vol 46, Issue 3 414-420, Copyright © 1997 by American Diabetes Association
Effects of multiple daily insulin injections and intraperitoneal insulin therapy on cholesteryl ester transfer and lipoprotein lipase activities in NIDDM
JD Bagdade, DE Kelley, RR Henry, RH Eckel and MC Ritter
Department of Medicine, Rush Medical College, Chicago, Illinois, USA.
Although the relationship between the actions of cholesteryl ester transfer
protein (CETP) and atherosclerosis is complex, a strong body of evidence
suggests that its activity (cholesteryl ester transfer [CET]) is
proatherogenic. We have previously shown that CET is increased in IDDM
patients receiving conventional subcutaneous insulin treatment and
normalized when systemic insulin levels are lowered with intraperitoneal
insulin delivery (IP). Since CET has been found by many observers to also
be accelerated in NIDDM, we sought to determine whether the same salutary
effect could be achieved in insulin-requiring NIDDM men before and 7 months
after randomization to an intensive treatment regimen (Rx) of either IP (n
= 9) or multiple daily insulin injections (MDI; n = 13). HbA1c improved to
the same degree in both groups (MDI group: 9.4 +/- 1.1% pre-Rx vs. 7.2 +/-
0.7% post-Rx [P < 0.001]; IP group: 9.2 +/- 1.3% pre-Rx vs. 7.1 +/- 0.5%
post-Rx [P < 0.001]). Compared with pre-Rx levels, plasma triglycerides
were not significantly changed by either treatment (MDI group: 136 +/- 80
mg/dl pre-Rx vs. 139 +/- 87 mg/dl post-Rx; IP group: 157 +/- 63 mg/dl
pre-Rx vs. 188 +/- 89 mg/dl post-Rx), though an upward trend followed IP.
Before randomization, CET estimated with both mass and isotopic assays was
greater in the NIDDM subjects than in nondiabetic control subjects (P <
0.001). With improved glycemic control, CE mass transfer declined in both
groups, but only reached normal levels in the IP group (MDI group at 2 h:
49.0 +/- 13.7 [mean +/- SD] pg pre-Rx vs. 29.5 +/- 15.3 microg post-Rx
[-39.7%, P < 0.01]; IP group at 2 h: 40.8 +/- 23.3 microg pre-Rx vs.
10.9 +/- 6.5 microg post-Rx [-73.2%, P < 0.05]) and remained abnormally
increased (P < 0.005) in the subjects receiving MDI. Total lipolytic
activity after intensive treatment was unchanged from pretreatment levels,
which were similar to those of the reference group. Although directional
changes in lipoprotein lipase (LpL) and hepatic triglyceride lipase (HTGL)
similar to those found in IDDM after MDI and IP were observed, they were
not statistically significant. Thus, while improved glycemic control alone
achieved by either MDI or IP reduced the pathological increase in CET in
these insulin-treated NIDDM men, normalization was only achieved in those
treated with IP. Despite near-normal HbA1c levels, CET remained abnormally
increased in NIDDM patients treated rigorously with conventional
subcutaneous insulin delivery.