EFFECT OF METFORMIN ON LIPOPROTEIN PARTICLE CONCENTRATION IN PEDIATRIC CARDIOMETABOLIC PATIENTS
Tara L. Dall,1 Madhuri M. Vasudevan,2 Christie M. Ballantyne,2 Ray Pourfarzib,3
1. Advanced Lipidology, Delafield, WI; 2. Baylor College of Medicine and Methodist DeBakey Heart Center, Houston, TX; 3. LipoScience, Inc., Raleigh, NC
As the incidence of childhood obesity continues to
Patient Selection and Study Design. A total of 78 pediatric Baseline Characteristics. In the metformin plus TLC and TLC
The obesity epidemic and associated comorbidities in
1. Troiano RP, Flegal KM. Overweight children and adolescents:
increase globally to near epidemic proportions, there is an
patients were seen in the lipid clinic over the period of January 2006
group, the mean age was 12.5 and 12 years of age, respectively
children is particularly concerning as these patients are likely
description, epidemiology, and demographics. Pediatrics
through May 2008. A retrospective chart review was conducted in
(Table 4). For all of the subjects (N= 20) at the initial visit there was
associated increase in the prevalence of metabolic syndrome
to have long term cardiovascular and diabetes risk. Based on
the office and 20 patients met the study criteria and were eligible for
discordance between LDL-P versus LDL-C and non-HDL-C (Table
and Type 2 diabetes in adolescence. In the past 20 years, the
our study findings many of these children were noted to have
2. Dabelea D, Pettit DJ, Jones KL, Arslanina SA. Type 2 Diabetes
the analysis (Table 1). The criteria for analysis included patients with
5). Comparing LDL-C less than 110 mg/dL and LDL-P less than
Mellitus in Minority Children and Adolescents. Endorinol Metab Clin
prevalence of an adolescent with a body mass index (BMI)
increased atherogenic risk as defined by high number of LDL
increased cardiometabolic risk and at least 2 available NMR lipoprotein
1100 nmol/L, 68% of the subjects had LDL-C less than 110 mg/dL
above the 95th percentile has increased by more than 50%.1,2
particles that were not identified by traditional LDL cholesterol
data sets in the time course specified. Increased cardiometabolic
and 15% of the subjects had LDL-P less than 1100 nmol/L.
3. Wilmshurst P. Heart Protection Study. Lancet 2003;361:528-529.
Although statin therapy has been shown in small studies to
risk was defined as having one or more of the following: diabetes,
At baseline, there were no significant differences in lipid levels
measurements. Treatment of lipid disorders in children has to
4. Ridker PM, Danielson E. Fonseca FAH, Genest J et al. Rosuvastatin
improve insulin resistance, recent large randomized trials in
obesity, family history of premature cardiovascular disease, impaired
between those selected for treatment with TLC alone, versus those
date focused on TLC and statin therapy. Statins are proven to
to Prevent Vascular Events in Men and Women with Elevated
adults showed no benefit.3,4 Metformin therapy in adults with
fasting glucose or lipid abnormalities on traditional lipid panel or
selected for treatment with metformin plus TLC, except for LDL-C,
reduce LDL but do not prevent diabetes. Metformin has been
C-Reactive Protein. NEJM 2008;359:2159-2207.
metabolic syndrome has favorable effects on glycemic control,
at least 2/3 metabolic markers on NMR lipoproteins (small dense
which was higher (p=0.037) in the metformin plus TLC-treated group
shown to slow progression to diabetes in previously published
5. Orchard TJ, Temprosa M, Goldberg R, Haffner S, Ratner R,
weight and lipid parameters.5 Metformin hydrochloride is an oral
Marcovina S, Fowler S. The Diabetes Prevention Program Research
LDL-P predominance, reduced large HDL P, excess large VLDL-P).
(average LDL-C 114.45 mg/dL) compared to the LDL-C level in the
studies. Metformin has also been shown have beneficial effects
Group: The effect of metformin and intensive lifestyle intervention
antihyperglycemic agent that has been prescribed for over 40
The treating physician abstracted the data from the patient’s medical
TLC treated group (average LDL-C 85.75 mg/dL). In the TLC-treated
on lipids as well as long term CV event reduction as studied in
on the metabolic syndrome: the Diabetes Prevention Program
years. It is now available as an inexpensive generic in both short
group, small LDL-P decreased by 21% (p=0.022) after an average 5.4
Randomized Trial. Ann Intern Med 2005;142:611-19. Defining Treatment Goals. All pediatric patients presenting to
months of therapy. In the metformin plus TLC-treated group, after
Strong evidence now exists in the benefit of LDL-P
6. Bailey CJ, Turner R. Metformin. The New England Journal of
the lipid clinic received trial of therapeutic lifestyle changes as noted
an average 6.7 months of therapy, large HDL-P increased by 47 %
Despite the success of cholesterol screening and low-
measurement in management of CVD. What we have found in
in table 2. Subjects were then assigned to receive either metformin
(p=0.037), LDL particle number decreased by 34% (p=0.002), small
density lipoprotein cholesterol (LDL-C) lowering therapy in the
our adult population is that patients with predominantly small
7. Kenneth J, Silva A, Robert M, et al. Effect of Metformin in Children
with diet and exercise (TLC) or TLC alone. The protocol for assigning
LDL-P decreased by 57% (p=0.002), LDL particle size increased by
diabetic population, it has been recognized that many patients
LDL particles and total LDL particles in excess have favorable
With Type 2 Diabetes. Current Diabetes Reports 2001;1:9-10.
patients to one of these two groups is detailed in table 3.
5% (p=0.001), LDL-C decreased by 14% (p=0.025), total cholesterol
with low or moderate LDL-C levels still experience CHD events.8,9
8. Jeyarajah EJ, Cromwell WC, Otvos JD. Lipoprotein particle analysis
The patients were seen at varying frequency, but most were
decreased by 8% (p=010), and Non-HDL-C decreased by 16%
lipoprotein/lipid changes with treatment of insulin resistance with
by nuclear magnetic resonance spectroscopy. Clin Lab Med
The limitation of testing LDL-C is that cholesterol is only one
seen every 4-8 weeks. Based on criteria listed in table 3 some
(p=0.001). In the metformin plus TLC treated group, although there
agents such as metformin or pioglitazone in addition to TLC.
type of lipid carried within low-density lipoprotein particle
patients were placed on metformin therapy in addition to TLC after
was a 21% increase in HDL-C, this did not reach clinical significance.
If LDL-P, triglycerides, and HDL normalize with this treatment
9. Garvey WT, Kwon S, Zheng D, et al. The effects of insulin resistance
(LDL-P) “containers” and its measurement provides only an
initial dietary trial. All patients were started on once daily metformin
No significant differences were found in TG levels, large VLDL-P,
option, a need for additional higher cost lipid lowering agents
and Type 2 diabetes mellitus on lipoprotein subclass particle size and
approximation of the numbers of LDL particles.10
500 mg with titration to 500 mg twice daily as tolerated, typically
glucose, HbA1C or weight before and after therapy in the metformin
concentration determined by nuclear magnetic resonance. Diabetes
To our knowledge, no study to date has directly addressed the
in 2-4 weeks. Goal of treatment was weight loss and improvement
Moreover, the discordance in LDL-C and LDL-P as well as
question of the effect of metformin on LDL particle concentration
in lipoprotein parameters with optimal LDL-P <1100 nmol/L. This is
During therapy, total LDL-P decreased 34% in the metformin
Non-HDL-C and LDL-P is expected in the setting of metabolic
10. Brunzell, J, Davidson, M, Furberg, C, et al. Lipoprotein Management
based on NCEP pediatric lipid guidelines of LDL-C <110 mg/dL.11
treated group (p=0.002). Small LDL-P (p < 0.005), LDL-C (p < 0.05),
measured by nuclear magnetic resonance (NMR) in the pediatric
syndrome or diabetes.13,14 Metformin plus TLC was very effective
in Patients With Cardiometabolic Risk. Diabetes Care 2008;4:811-
Laboratory Analysis. All lipid and lipoprotein particle analyses
and Non-HDL-C (p < 0.005) also decreased in the metformin treated
population with metabolic syndrome. Hence, the aim of this study
in decreasing small LDL-P, increasing large HDL-P and decreasing
were conducted on the same plasma specimens by the same
patients (-57%, -14%, -16%, respectively). Large HDL-P value
11. Daniels SR, Greer FR. Committee on Nutrition 2008 Lipid screening
was to examine the discordance between LDL-C and LDL-P
large VLDL-P values which is also associated with a decrease
laboratory. Total cholesterol, triglycerides, and HDL cholesterol
and cardiovascular health in childhood. Pediatrics 2008;122:198–
in adolescent patients with increased cardiometabolic risk and
in total LDL-P, weight loss, and often drop in triglycerides and
(HDL-C) were measured by standardized automated methods, and
In the TLC group at baseline, the mean values for LDL-C, non-
to compare the effects of metformin plus TLC therapy versus
LDL-C was calculated by the Friedewald equation.12 Concentrations
HDL-C, and LDL-P were approximately at the 10th, 30th, and 55%
non-HDL-C. With the rising epidemic of pediatric obesity and
12. Friedewald WT, Levy RI, Fredrickson DS. Estimation of the
TLC therapy alone on standard lipid profile measurements and
concentration of low-density lipoprotein cholesterol in plasma,
of LDL-P were determined by automated nuclear magnetic resonance
percentile of the population, respectively. As expected, the mean
comorbities of metabolic syndrome, diabetes, and dyslipidemia,
lipoprotein particle number and size as measured through the
without use of the preparative ultracentrifuge. Clin Chem
values for LDL-C, non-HDL-C and LDL-P were also lower compared
we need to find alternative clinical approaches. Treatment of
NMR LipoProfile® test analyzer. Statistical Analysis. Nine subjects were selected to
to the metformin plus TLC group (86 mg/dL, 129 mg/dL, 1457 nmol/L,
dyslipidemia in children currently is focused on TLC and statins.
13. Cromwell WC, Otvos JD, Keyes M, Pencina M, Sullivan L, Vasan
receive TLC, and 11 subjects were selected to receive metformin
respectively). Furthermore, there was no significant change in the
However, the underlying cause of dyslipidemia in these children
R, Wilson P, D’Agostino R. LDL Particle Number and Risk of Future
plus TLC. Homoscedastic student’s t-test was used to compare the
TLC group for all lipid and lipoprotein values except a significant
is often insulin resistance. Therefore, we believe this condition
Cardiovascular Disease in the Framingham Offspring Study-
differences in lipoprotein parameters between TLC-treated subjects
drop in the small LDL-P (-21%, p < 0.05).
can be cost effectively treated with TLC and Metformin to lower
Implications for LDL Management. J of Clinical Lip 2007;1:583-592.
and metformin plus TLC-treated subjects at baseline visit. A paired
their lipids and improve their weight loss.
14. Otvos, J Collins D, Freedman D, Shalaurova I, Schaefer E, McNamara
student’s t-test was used to compare the differences in lipoprotein
J, Bloomfield H, Robins S. VA-HIT: Low Density Lipoprotein and
parameters in TLC-treated patients before and after therapy, and
High Density Lipoprotein Particle Subclasses Predict Coronary
compare metformin plus TLC-treated subjects before and after
Events. Circulation 2006;113:1556-1563.
TABLE 3 : Criteria for Patient Selection for Treatment with
TABLE 5 : Percent of Subjects with Discordance Between LDL-C, Non-HDL-C, and LDL-P
Goals and their Perspective Percent Population Distribution During Initial Visit
• Pediatric population- ages 4 to 18 years of age
• low HDL, <40 mg/dL males <50 mg/dL females and elevated
• Baseline and follow-up NMR LipoProfile test results available for
LDL-C < 110 mg/dL .68% . 102 mg/dL . ~ 20%
• elevated small particles where the majority of the total LDL-P were
• Diagnosis of increased cardiometabolic risk defined as having any
LDL-P < 1100 nmol/L .15% . 1650 nmol/L . ~ 70%
one of the following: diabetes, obesity, impaired fasting glucose or
lipid abnormalities on traditional lipid panel or at least 2/3 metabolic
• age (children were not started on metformin strictly because < 10
markers on NMR (small dense LDL-P predominance, reduced
TABLE 6 : Percent Change of Various Values Between the Metformin + TLC vs. TLC Group from Baseline to Follow-Up visit
large HDL P, excess large VLDL-P), family history of premature
• physical exam showing acanthosis nigricans, a clinical sign of insulin
TABLE 2 : TLC - Patient Management Protocol (Specific TLC Recommendations)
First Visit:
• Exercise: based on an assessment of each individual patient
• Parents and patients were informed that this was family program and
according to likes, current activity levels, family schedules and
it was expected that everyone in the family make changes and child
• Limit sedentary activities including television, computer not being
• Read labels on every item purchased; patients were given a detailed
used for homework, video games limited to no more than 1 hour on
handout on reading labels that was specific to looking for added sugar,
school nights and no more than 2 hours on weekend days
high fructose corn syrup, sat fat and partially hydrogenated oil
Second Visit:
• Avoid High fructose corn syrup, limit added sugar to no more than 4-6
• Limit portions- used division of 9” plate into fourths; half with non-
starchy vegetable; ¼ protein 6 oz; ¼ grain or starchy vegetable
• Avoid partially hydrogenated oils and limit sat fats to no more than 3
• Insoluble fiber intake: age plus 5 grams minimum and soluble fiber 10
• Increase vegetable intake: Assignments for trying one new vegetable
• Incorporating legume type beans into diet
every week and reporting back what the vegetable was, how it was
cooked and whether child liked it or not.
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