Relationship between total vitamin D metabolites and complications in patients with type 2 diabetes.

In our previous study, it was shown that endogenous vitamin D3 and its metabolites are associated with diabetic microvascular complications and cardiovascular risk factors. The aim of the present study was to determine if the relationship between total vitamin D (vitamin D2 supplements plus endogenous vitamin D3) was a better predictor of complications in type 2 diabetes (T2DM). A total of 460 patients with T2DM participated in the present cross-sectional study. Plasma levels of total vitamin D and its metabolites (1,25-dihydroxyvitamin D (1,25(OH)D), 25-hydroxyvitamin D (25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)D) were measured by isotope-dilution liquid chromatography tandem mass spectrometry analysis. 1,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 were associated with diabetic retinopathy and coronary artery disease, but total 1,25-dihydroxyvitamin D and total 25-hydroxyvitamin D levels were not statistically associated with any complications. Total 1,25-dihydroxyvitamin D showed the same positive association as 1,25-dihydroxyvitamin D3 for hypertension and dyslipidemia, and total 25-hydroxyvitamin D showed the same positive association as 25-hydroxyvitamin D3 for dyslipidemia. Total 24,25-dihydroxyvitamin D showed the same positive association only with dyslipidemia as did 24,25-dihydroxyvitamin D3. However, total 25-hydroxyvitamin D was associated with hypertension, whereas 25-hydroxyvitamin D3 was not. Vitamin D3 metabolites were associated with diabetic retinopathy, whereas total vitamin D levels were not, suggesting that endogenous vitamin D3 metabolites are a better measure of diabetic microvascular complications. However, both total vitamin D and vitamin D3 metabolites were associated with cardiovascular risk factors in patients with type 2 diabetes.

Vitamin D3 metabolite ratio as an indicator of vitamin D status and its association with diabetes complications.

BACKGROUND: Vitamin D deficiency is diagnosed by total serum 25-hydroxyvitamin D (25(OH)D) concentration and is associated with poor health and increased mortality; however, some populations have low 25(OH) D concentrations without manifestations of vitamin D deficiency. The Vitamin D Metabolite Ratio (VMR) has been suggested as a superior indicator of vitamin D status. Therefore, VMR was determined in a population with type 2 diabetes at high risk for vitamin D deficiency and correlated with diabetic complications. RESEARCH DESIGN AND METHODS: Four hundred sisty patients with type 2 diabetes (T2D) were recruited, all were vitamin D3 supplement naive. Plasma concentration of 25-hydroxyvitamin D3 (25(OH)D3) and its metabolites 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) and its epimer, 3-epi-25-hydroxyvitamin D3 (3-epi-25(OH)D3), were measured by LC-MS/MS analysis. VMR-1 was calculated as a ratio of 24,25(OH)2D3:25(OH)D3; VMR-2 as a ratio of 1,25(OH)2D3:25(OH)D3; VMR-3 was calculated as a ratio of 3-epi-25(OH)D3: 25(OH)D3. RESULTS: An association means that there were significant differences between the ratios found for those with versus those without the various diabetic complications studied. VMR-1 was associated with diabetic retinopathy (p = 0.001) and peripheral artery disease (p = 0.012); VMR-2 associated with hypertension (p < 0.001), dyslipidemia (p < 0.001), diabetic retinopathy (p < 0.001), diabetic neuropathy (p < 0.001), coronary artery disease (p = 0.001) and stroke (p < 0.05). VMR-3 associated with hypertension (p < 0.05), dyslipidemia (p < 0.001) and coronary artery disease (p < 0.05). CONCLUSIONS: In this cross sectional study, whilst not causal, VMR-2 was shown to be the superior predictor of diabetic and cardiovascular complications though not demonstrative of causality in this cross-sectional study population over VMR-1, VMR-3 and the individual vitamin D concentration measurements; VMR-2 associated with both microvascular and cardiovascular indices and therefore may have utility in predicting the development of diabetic complications.

Association of vitamin D2 and D3 with type 2 diabetes complications.

AIMS: Vitamin D measurement is a composite of vitamin D2 (25(OH)D2) and D3 (25(OH)D3) levels, and its deficiency is associated with the development of type 2 diabetes (T2DM) and diabetic complications; vitamin D deficiency may be treated with vitamin D2 supplements. This study was undertaken to determine if vitamin D2 and D3 levels differed between those with and without T2DM in this Middle Eastern population, and the relationship between diabetic microvascular complications and vitamin D2 and vitamin D3 levels in subjects with T2DM. METHODS: Four hundred ninety-six Qatari subjects, 274 with and 222 without T2DM participated in the study. Plasma levels of total vitamin D2 and D3 were measured by LC-MS/MS analysis. RESULTS: All subjects were taking vitamin D2 and none were taking D3 supplements. Vitamin D2 levels were higher in diabetics, particularly in females, and higher levels were associated with hypertension and dyslipidemia in the diabetic subjects (p < 0.001), but were not related to diabetic retinopathy or nephropathy. Vitamin D3 levels measured in the same subjects were lower in diabetics, particularly in females (p < 0.001), were unrelated to dyslipidemia or hypertension, but were associated with retinopathy (p < 0.014). Neither vitamin D2 nor vitamin D3 were associated with neuropathy. For those subjects with hypertension, dyslipidemia, retinopathy or neuropathy, comparison of highest with lowest tertiles for vitamin D2 and vitamin D3 showed no difference. CONCLUSIONS: In this Qatari cohort, vitamin D2 was associated with hypertension and dyslipidemia, whilst vitamin D3 levels were associated with diabetic retinopathy. Vitamin D2 levels were higher, whilst vitamin D3 were lower in diabetics and females, likely due to ingestion of vitamin D2 supplements.

Perceptions and attitudes to clinical research participation in Qatar.

Recruitment into clinical research studies is a major challenge. This study was carried out to explore the perceptions and attitudes towards clinical research participation among the general public in Qatar. A population based questionnaire study was carried out at public events held in Qatar. Residents of Qatar, 18 years or above in age were surveyed, anonymously, following verbal consent. Descriptive and multivariate analyses were conducted. We administered 2517 questionnaires to examine clinical research participation, of which 2379 complete forms were analyzed. Those who had previously been approached to participate in research completed a more detailed assessment. Data showed that only 5.7% participants (n = 134) had previously been approached to participate in a clinical research study. Of these 63.4% (n = 85) had agreed to participate while 36.6% (n = 49) had declined. The main reasons for declining participation included: time constraint (47.8%, n = 11), 'fear' (13.0%, n = 3), lack of awareness about clinical research (8.7%, n = 2) and lack of interest (8.7%, n = 2). 'To help others' (31.8%, n = 27) and 'thought it might improve my access to health care' (24.7%, n = 21) were the prime motivators for participation. There was a general agreement among participants that their previous research experience was associated with positive outcomes for self and others, that the research conduct was ethical, and that opportunities for participation will be welcomed in future. More than ten years of stay within Qatar was a statistically significant determinant of willingness to participate, adjusted odds ratio 5.82 (95% CI 1.93-17.55), p = 0.002. Clinical research participation in Qatar needs improvement. Time constraints, lack of trust in and poor awareness about clinical research are main barriers to participation. Altruism, and improved health access are reported as prime motivators. Deeper insight in to the factors affecting clinical research participation is needed to devise evidence based policies for improvement in recruitment strategies.