The trial did not find a significant effect of atorvastatin treatment with regard to
the primary endpoint, i.e. the comparison of stimulated C-peptide concentrations
between groups at 18 months. Also, the two groups did not differ significantly with
regard to fasting C-peptide levels. In both cases, median C-peptide concentrations
were around 50% higher in the atorvastatin than the placebo group at 18
months, but this difference failed to be significant because of an unexpectedly
large range or standard deviation of C-peptide concentrations measured, in both
groups. In this regard, a major limitation of the trial is that the actual number of
patients recruited was lower than foreseen in the study protocol (total 89 vs.
160).
As secondary analysis we compared median C-peptide concentrations over the study
period within a group. There was a significant deterioration of residual beta cell
function in the placebo group but not the atorvastatin group. In the placebo group,
median fasting C-peptide concentrations decreased from baseline by 32% at 12
months and by 41% at 18 months (p<0.001), whereas there was no significant
change in the atorvastatin group. Median stimulated C-peptide concentrations
decreased mildly in both groups by 12 months (by 20% in the placebo group and
by 17% in the atorvastatin group, p<0.01 each). At 18 months median
C-peptide concentrations had further decreased (p

=

0.046),
total decrease by 46% of baseline, whereas there was no further deterioration
in the atorvastatin group, total decrease by 19%.
These differences were not reflected by lower insulin doses in the atorvastatin
group. Rather, there was a more rapid increase of insulin dosing leading to
significantly higher insulin doses at 12 months although not at 18 months. Some
types of statins have been reported to increase or decrease insulin resistance but a
consistent effect was not noted for atorvastatin in a recent meta-analysis
[19]. Partial
preservation of residual beta cell function is considered as clinically relevant
goal also in the absence of lower insulin requirements, because of a lower risk of
complications
[20],
[21].
Since beta cell function is affected by the concentration of glucose at the start of
the test, the study protocol requested that no mixed meal test should be performed
if fasting blood glucose was outside 4–11 mmol/l. However, even in this
concentration range, ambient glucose may affect the outcome of beta cell function
tests, as suggest by the recent international workshop comparing the liquid mixed
meal with the glucagon assay
[22]. There was an inverse relationship between fasting blood
glucose and subsequent peak C-peptide concentrations following the liquid mixed
meal. This means that the higher HbA1c levels (and consequently higher mean fasting
blood glucose levels) in the atorvastatin group at 12 and 18 months probably has led
to a lower C-peptide response, and hence has downsized the difference between the
two groups. Unfortunately, there is no algorithm or formula for adjusting C-peptide
responses for ambient glucose.
As expected, regular intake of atorvastatin caused a decrease of total and
LDL-cholesterol levels in serum, a decrease of triglyceride levels and a small
increase of HDL-cholesterol levels. Median concentrations of CRP were low at
baseline, but were further lowered by statin treatment. All of these effects are
consequences of inhibiting the synthesis of mevalonate from acetyl coenzyme A by
hydroxyl-3-methylglutaryl-coenzyme A reductase. This is a rate limiting step in
cholesterol synthesis, and the mevalonate pathway gives rise to a number of
compounds such as farnesyl or geranylgeranyl pyrophosphate which can modify several
transcription factors controlling cell growth, endothelial activity and immune gene
expression
[3],
[23]–
[26]. The
amelioration of the lipid status by atorvastatin treatment may be considered
advantageous, independent of the slowed loss of beta cell function. The decrease in
systemic CRP levels may indicate a dampening of inflammatory processes, although our
analysis of circulating concentrations of 14 different immune mediators, including
soluble adhesion molecules, cytokines, a cytokine antagonist and chemokines did not
reveal statin-treatment associated changes. This argues against a major effect on
systemic immune reactivity but does not exclude that statin treatment affects
islet-antigen specific cellular immunity, e.g. through an increase of regulatory
T-cell functions in pancreatic islets or draining lymph nodes. Indeed, statin
blockade of the mevalonate pathway has been observed to promote the generation of
Foxp3 positive regulatory T-cells in mice and a shift from autoaggressive Th1 to
more benign Th2 immunity
[27]–
[30]. Atorvastatin-induced Krüppel-like factor 2
expression may be a critical event for these effects
[31]. Besides the immunomodulatory
properties atorvastatin may also target pancreatic islets. A recent study in
streptozotocin treated rat pups reported an increase in the number of small islets
following atorvastatin treatment, suggestive of neogenesis. Since angiogenesis
preceded the increase in beta cell mass, target of atorvastatin may be the
endothelium
[32].
Atorvastatin was generally well tolerated. Dose reductions or temporary
discontinuation of treatment were reported in 8 cases, in three cases treatment was
permanently discontinued. Elevation of CPK levels were observed more often in the
atorvastatin than in the placebo group (35 vs 14%) but did not reach critical
levels of >2000 U/l.
In summary, we report that treatment with atorvastatin over 18 months was safe and
well tolerated in adult patients with recent-onset type 1 diabetes. At 18 months,
the atorvastatin group did not exhibit significantly higher fasting or stimulated
C-peptide concentrations than the placebo group. Secondary analyses of the course of
C-peptide secretion within groups found some preservation of fasting and stimulated
serum C-peptide concentrations in the atorvastatin but not the placebo group. A
comparison with results from the ongoing trial of atorvastatin in children and
adolescents with type 1 diabetes (ClinicalTrials.gov registration number
NCT00529191) will help to judge the potential of this treatment modality.