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Association between serum prolactin levels and insulin resistance in non-diabetic men

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ABSTRACT

Prolactin (PRL) has roles in various physiological functions. Although experimental studies showed that PRL has both beneficial and adverse effects on type 2 diabetes mellitus, clinical findings in subjects with hyperprolactinemia indicate adverse effects on glucose metabolism. However, effects of PRL within the physiological range in human are controversial. A population-based study of 370 Japanese men enrolled in the 2014 Iwaki study (aged 52.0 ± 14.8 years). In this cross-sectional study, associations between serum PRL levels and homeostatic model assessment (HOMA) indices representing glucose metabolism in a physiological setting were examined using multivariable regression analysis. Although univariate linear regression analyses showed significant associations between serum PRL levels and HOMA indices, adjustment with multiple factors made the association with HOMA-ß (insulin secretion) insignificant, while those with HOMA-R (insulin resistance) remained significant (ß = 0.084, p = 0.035). Non-linear regression analyses showed a regression curve with a peak at serum PRL level, 12.4 ng/mL and a positive association of serum PRL level with HOMA-R below the peak (ß = 0.119, p = 0.004). Higher serum PRL levels within the physiological range seem to be associated with insulin resistance in men.

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Related in: MedlinePlus

Non-linear regression analyses with curve fitting with the Gaussian model.Correlations between serum prolactin (PRL) levels and insulin resistance index assessed by homeostasis model (HOMA-R) are shown. The arrow indicates a peak on the regression curve for men at a serum PRL level 12.4 ng/mL.
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pone.0175204.g001: Non-linear regression analyses with curve fitting with the Gaussian model.Correlations between serum prolactin (PRL) levels and insulin resistance index assessed by homeostasis model (HOMA-R) are shown. The arrow indicates a peak on the regression curve for men at a serum PRL level 12.4 ng/mL.

Mentions: As shown in Fig 1, graphs of the data points appeared to support such correlation between serum PRL levels and HOMA-R. Further, the graph indicates that the correlation may not form a straight line. Thus, we examined the correlations with non-linear regression analyses, which showed a regression curve with a peak at a serum PRL level of 12.4 ng/mL. When subjects were stratified based on serum PRL levels, p values for the positive correlation between serum PRL level and HOMA-R decreased further, even after adjustment for multiple factors in subjects whose serum PRL level was below the peak (ß = 0.119, p = 0.004), while such correlations were not observed in subjects whose serum PRL level was above the peak (Table 2). These findings were further verified by additional analyses in which subjects were divided into halves (high vs. low) in each stratified group. From these analyses, it was found that high serum PRL levels significantly correlated with HOMA-R even after adjustment for multiple factors in subjects whose serum PRL level was below the peak (ß = 0.082, p = 0.046), while such correlations were not observed in subjects whose serum PRL level was above the peak (Table 2).


Association between serum prolactin levels and insulin resistance in non-diabetic men
Non-linear regression analyses with curve fitting with the Gaussian model.Correlations between serum prolactin (PRL) levels and insulin resistance index assessed by homeostasis model (HOMA-R) are shown. The arrow indicates a peak on the regression curve for men at a serum PRL level 12.4 ng/mL.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5383244&req=5

pone.0175204.g001: Non-linear regression analyses with curve fitting with the Gaussian model.Correlations between serum prolactin (PRL) levels and insulin resistance index assessed by homeostasis model (HOMA-R) are shown. The arrow indicates a peak on the regression curve for men at a serum PRL level 12.4 ng/mL.
Mentions: As shown in Fig 1, graphs of the data points appeared to support such correlation between serum PRL levels and HOMA-R. Further, the graph indicates that the correlation may not form a straight line. Thus, we examined the correlations with non-linear regression analyses, which showed a regression curve with a peak at a serum PRL level of 12.4 ng/mL. When subjects were stratified based on serum PRL levels, p values for the positive correlation between serum PRL level and HOMA-R decreased further, even after adjustment for multiple factors in subjects whose serum PRL level was below the peak (ß = 0.119, p = 0.004), while such correlations were not observed in subjects whose serum PRL level was above the peak (Table 2). These findings were further verified by additional analyses in which subjects were divided into halves (high vs. low) in each stratified group. From these analyses, it was found that high serum PRL levels significantly correlated with HOMA-R even after adjustment for multiple factors in subjects whose serum PRL level was below the peak (ß = 0.082, p = 0.046), while such correlations were not observed in subjects whose serum PRL level was above the peak (Table 2).

View Article: PubMed Central - PubMed

ABSTRACT

Prolactin (PRL) has roles in various physiological functions. Although experimental studies showed that PRL has both beneficial and adverse effects on type 2 diabetes mellitus, clinical findings in subjects with hyperprolactinemia indicate adverse effects on glucose metabolism. However, effects of PRL within the physiological range in human are controversial. A population-based study of 370 Japanese men enrolled in the 2014 Iwaki study (aged 52.0 ± 14.8 years). In this cross-sectional study, associations between serum PRL levels and homeostatic model assessment (HOMA) indices representing glucose metabolism in a physiological setting were examined using multivariable regression analysis. Although univariate linear regression analyses showed significant associations between serum PRL levels and HOMA indices, adjustment with multiple factors made the association with HOMA-ß (insulin secretion) insignificant, while those with HOMA-R (insulin resistance) remained significant (ß = 0.084, p = 0.035). Non-linear regression analyses showed a regression curve with a peak at serum PRL level, 12.4 ng/mL and a positive association of serum PRL level with HOMA-R below the peak (ß = 0.119, p = 0.004). Higher serum PRL levels within the physiological range seem to be associated with insulin resistance in men.

No MeSH data available.


Related in: MedlinePlus