4.2 | Results in the context of what is known
To our knowledge, there is no large-scale, population-based,
longitudinal study evaluating the association between presence of UL and
development of type 2 diabetes mellitus in young women. This study
revealed that UL was associated with an elevated risk for type 2
diabetes mellitus and that myomectomy seemed to attenuate the risk for
type 2 diabetes mellitus in young women with UL.
Several studies indicate an association between obesity and
UL.2,12,13 Ciavattni et al. performed an observational
case-control study including 71 women of childbearing age diagnosed with
UL and 145 women as control group.12 Women with UL had
higher BMI (P = 0.0034), preperitoneal fat thickness (P< 0.0001), and subcutaneous fat thickness (P = 0.0003);
however, only preperitoneal fat thickness showed an independent
significant association with the presence of UL in multivariate analysis
(P < 0.0001). Another study, including 89 patients with
UL and 81 healthy women without UL, showed that increased body fat
(especially abdominal visceral fat) is associated with an increased risk
of UL.13 Recently, a meta-analysis examining 24
studies found a positive association between obesity and the
risk/prevalence of UL (odds ratio [OR] 1.19, 95% CI
1.09-1.29).2 Consistent with the result of previous
studies, women with UL had a BMI higher than that of women without UL in
our study, although both groups had relatively low BMI. However, in
subgroup analysis stratified by BMI, women with BMI ≥25
kg/m2 revealed no significant difference in the
incidence rate of type 2 diabetes mellitus between women with UL and
without UL. This might be due to well-known close association between
obesity and the development of type 2 diabetes mellitus. Relative high
incidence rate of women with or without UL with BMI ≥25
kg/m2 compared to women with BMI less than 25
kg/m2 support this hypothesis (Table 3). Similarly,
there was no difference in the incidence rate of type 2 diabetes
mellitus between women with UL and without UL in whom with CKD history.
These findings also might be due to the inseparable association between
CKD and development of type 2 diabetes mellitus.14
Beyond obesity, several studies reported that various metabolic
components were associated with UL.10,15 Takeda et al
investigated whether UL is associated with any specific criteria of
metabolic syndrome.15 In their case-control study,
BMI, blood pressure, TG, and FPG were significantly higher in 213 women
with UL compared to those in 159 women without UL. Moreover, the risk of
UL was correlated with increased metabolic component levels; the OR of
three metabolic components for UL was 3.64 (95%CI 2.28-5.82). Another
study that enrolled 1,230 parous premenopausal women reported that women
with UL had higher waist circumferences, body fat, blood pressure, and
LDL cholesterol than women without UL.10 Increasing
evidence suggests that UL seems to share pathogenic features with the
development of metabolic syndrome. In our study, women with UL had poor
metabolic profiles, such as higher blood pressure, FPG, total
cholesterol, TG, LDL cholesterol, and lower HDL cholesterol, when
compared with women without UL.
Although the two disease states are likely to be related, few studies
have evaluated the association between UL and type 2 diabetes mellitus.
A nested case-control study enrolling 3,789 participants reported a
protective association between UL and type 2 diabetes with a relatively
greater protective effect observed among European Americans than African
Americans.16 However, this study was limited by design
and population as it was a cross-sectional study that included
relatively old women (mean age: 47 y in UL group; 44 y in control
group). On the other hand, the previously mentioned study by Tak et al
revealed that hyperglycemia is significantly associated with an
increased risk of UL (OR: 1.45, 95%CI 1.10-1.89).10Furthermore, in a Taiwanese population-based cohort study, metformin use
was associated with a lower risk of UL (HR: 0.467, 95%CI 0.387-0.564)
in 21,996 women with new-onset type 2 diabetes
mellitus.11 However, there was no longitudinal study
to evaluate the risk for type 2 diabetes mellitus solely in connection
with the presence of UL, especially in young women.