1.
Dose-response association between the triglycerides: High-density lipoprotein cholesterol ratio and type 2 diabetes mellitus risk: The rural Chinese cohort study and meta-analysis.
Cheng, C, Liu, Y, Sun, X, Yin, Z, Li, H, Zhang, M, Zhang, D, Wang, B, Ren, Y, Zhao, Y, et al
Journal of diabetes. 2019;(3):183-192
Abstract
BACKGROUND High triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C) levels are traditional risk factors for type 2 diabetes mellitus (T2DM). This study evaluated the dose-response relationship between the TG/HDL-C ratio and T2DM risk. METHODS The study included 11 946 adults without baseline diabetes from the Rural Chinese Cohort Study. Cox proportional hazards regression was used to investigate the association between the TG/HDL-C ratio and T2DM. The dose-response relationship was evaluated by restricted cubic spline analysis. In addition, pooled odds ratios (OR) were calculated with a random-effects model in a meta-analysis including the present study and another three eligible articles. RESULTS During 2007-14, 618 patients with T2DM were identified (9.68/1000 person-years). People in the highest TG/HDL-C ratio quartile had a higher T2DM risk than those in the lowest quartile (adjusted hazard ratio [aHR] 2.11, 95% confidence interval [CI] 1.55-2.86); however, the association between the TG/HDL-C ratio and T2DM was stronger in females than males (aHR 1.27 [95% CI 1.16-1.39; and 1.19 [95% CI 1.04-1.37], respectively). In body mass index-specific analysis, the association was stronger in normal weight than overweight/obese people. The dose-response meta-analysis showed that a 1-unit increment in the TG/HDL-C ratio increased the T2DM risk by 28% (95% CI 20%-36%), with a positive linear relationship (Plinear = 0.326). CONCLUSIONS The TG/HDL-C ratio was an independent risk factor of T2DM, especially in females, and linearly increased the risk of T2DM; thus, it may be a useful indicator to identify future T2DM.
2.
Why should we measure free 25(OH) vitamin D?
Tsuprykov, O, Chen, X, Hocher, CF, Skoblo, R, Lianghong Yin, , Hocher, B
The Journal of steroid biochemistry and molecular biology. 2018;:87-104
Abstract
Vitamin D, either in its D2 or D3 form, is essential for normal human development during intrauterine life, kidney function and bone health. Vitamin D deficiency has also been linked to cancer development and some autoimmune diseases. Given this huge impact of vitamin D on human health, it is important for daily clinical practice and clinical research to have reliable tools to judge on the vitamin D status. The major circulating form of vitamin D is 25-hydroxyvitamin D (25(OH)D), although it is not the most active metabolite, the concentrations of total 25-hydroxyvitamin D in the serum are currently routinely used in clinical practice to assess vitamin D status. In the circulation, vitamin D - like other steroid hormones - is bound tightly to a special carrier - vitamin D-binding protein (DBP). Smaller amounts are bound to blood proteins - albumin and lipoproteins. Only very tiny amounts of the total vitamin D are free and potentially biologically active. Currently used vitamin D assays do not distinguish between the three forms of vitamin D - DBP-bound vitamin D, albumin-bound vitamin D and free, biologically active vitamin D. Diseases or conditions that affect the synthesis of DBP or albumin thus have a huge impact on the amount of circulating total vitamin D. DBP and albumin are synthesized in the liver, hence all patients with an impairment of liver function have alterations in their total vitamin D blood concentrations, while free vitamin D levels remain mostly constant. Sex steroids, in particular estrogens, stimulate the synthesis of DBP. This explains why total vitamin D concentrations are higher during pregnancy as compared to non-pregnant women, while the concentrations of free vitamin D remain similar in both groups of women. The vitamin D-DBP as well as vitamin D-albumin complexes are filtered through the glomeruli and re-uptaken by megalin in the proximal tubule. Therefore, all acute and chronic kidney diseases that are characterized by a tubular damage, are associated with a loss of vitamin D-DBP complexes in the urine. Finally, the gene encoding DBP protein is highly polymorphic in different human racial groups. In the current review, we will discuss how liver function, estrogens, kidney function and the genetic background might influence total circulating vitamin D levels and will discuss what vitamin D metabolite is more appropriate to measure under these conditions: free vitamin D or total vitamin D.