Vitamin D and Type 2 Diabetes

Sex-Specific Association between Serum 25-Hydroxyvitamin D and Metabolic Risk Factors in T2DM Patients

OBJECTIVE

To evaluate the relationship between serum 25-hydroxyvitamin (25(OH)D) levels and metabolic risk factor levels in patients with type 2 diabetes mellitus (T2DM) on a sex-specific basis.

METHODS

Our study comprised 507 patients with T2DM (321 men, 186 women; median age, 59 years). The metabolic risk factors examined included lipoprotein(a), glycated albumin (GA-L), and random blood glucose (RBG); the levels of these parameters were determined enzymatically. Serum 25(OH)D levels were measured by commercial ELISA kits. Participants were divided into low and high 25(OH)D groups according to the median 25(OH)D concentration (13.2 ng/mL). Two-way analysis of covariance and multiple linear regression analysis were performed.

RESULTS

The median 25(OH)D concentration was 13.9 ng/mL in men and 12.2 ng/mL in women. 25(OH)D levels inversely correlated with levels of three metabolic risk factors in a sex-dependent manner after adjusting for several confounding factors. These were lipoprotein(a) in men (141.3 ± 137.9 and 195.3 ± 204.8 mg/L in high and low 25(OH)D groups, respectively; P < 0.05); GA-L in women (22.2 ± 8.8 vs. 23.3 ± 7.3% in high and low 25(OH)D groups, respectively; P < 0.05). In a subgroup analysis, serum 25(OH)D levels inversely correlated with lipoprotein(a) levels in men (β = -0.185, P = 0.002) and RBG levels in women (β = -0.176, P = 0.028).

CONCLUSION

Higher serum 25(OH)D levels indicate a more favorable lipid profile in men and a more favorable glucose profile in women.

Association of Serum 25-Hydroxyvitamin D Concentrations With Glucose Profiles in Male Collegiate Football Athletes

Low serum 25-hydroxyvitamin D [25(OH)D] concentrations are associated with a high risk of insulin resistance and Type 2 diabetes mellitus in adults. However, it is unknown whether this is the case for American collegiate football and rugby football athletes. This study investigated the associations between serum 25(OH)D concentrations and glucose profiles in male collegiate football athletes. Thirty-four collegiate athletes (13 American football players and 21 rugby football players) aged 21 years were recruited. Their body fat percent and visceral fat area were measured by dual-energy X-ray absorptiometry and magnetic resonance imaging, respectively. The participants completed an oral glucose tolerance test (75 g glucose) with venous blood samples obtained at time points 0, 30, 60, 90, and 120 min for the determination of plasma glucose and serum insulin concentrations. Fasting serum 25(OH)D concentrations were also measured. The prevalence of vitamin D deficiency and insufficiency was 17.6% and 58.8%, respectively. The serum 25(OH)D concentrations were negatively associated with the increments in the areas under the curve (iAUC) for glucose (r = -.429, p = .011) and were borderline significantly correlated with the Matsuda index (r = -.303, p = .082). No relationships were observed between the serum 25(OH)D concentrations and other glucose profiles. Multiple stepwise regression analysis of glucose iAUC concentrations as the dependent variable indicated that the serum 25(OH)D concentrations, but not body fat indicators, were independently associated with glucose iAUC (β = -0.390, p = .025). The serum 25(OH)D concentrations were only an independent predictor for glucose iAUC in male collegiate football athletes, suggesting that increased 25(OH)D concentrations would be helpful for maintaining glucose homeostasis.

Study of the effect of the essential oil (extract) of rhubarb stem (shoot) on glycosylated hemoglobin and fasting blood glucose levels in patients with type II diabetes

BACKGROUND

Diabetes is a serious chronic disease that can damage the heart, arteries, eyes, kidneys and nerves, leading to death and early disability. Before the discovery of insulin as well as common anti-diabetes drugs, patients with diabetes were treated with medicinal herbs and traditional treatments. One of these effective medicinal herbs is Rhubarb. Rhubarb is prescribed in traditional medicine for various patients, including patients with diabetes. But its effect has not been scientifically reported so far.

PURPOSE

This study was conducted with the aim to determine the effectiveness of Rhubarb stem extract on HbA1C and fasting blood glucose in patients with type II diabetes.

METHOD

In this experimental study, 80 patients with type II diabetes mellitus in Zabol diabetes center, aged 30-60 years old with fasting blood glucose greater than 140 mg/d/ were selected. Patients were randomly assigned into two groups (n = 40) of treatment with capsules of Rhubarb stem and placebo after matching the oral medications. The patients in both groups were studied for fasting blood glucose and HbA1C before and after 1 month of conducting the study.

RESULTS

The mean FBS and HbA1C in rhubarb group before the intervention were 288.80 ± 94.49 and 9.62 ± 1.58, respectively, and after the intervention were 226.42 ± 88.89 and 7.83 ± 1.50, respectively. According to the statistical paired f-test and Wilcoxon test a significant reduction was found in FBS and HbA1C with rhubarb intervention (p < 0.05).

CONCLUSION

In diabetes mellitus, as many factors affect the level of blood glucose, they also contribute to reducing blood glucose level and preventing complications. Therefore, considering the positive effects of rhubarb, it can be recommended to use rhubarb extract as an additional treatment to reduce blood glucose level.

Effect of vitamin D supplementation on insulin resistance and glycaemic control in prediabetes: a systematic review and meta-analysis

AIMS

To evaluate the effect of vitamin D on insulin resistance and glycaemic control in prediabetes.

METHODS

A literature search was conducted of MEDLINE, the Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, Web of Science and www.clinicaltrials.gov, together with a historical search through the reference lists of relevant articles until end of June 2014. Studies were included if they were randomized controlled trials of vitamin D or vitamin D analogues in prediabetes and if they reported homeostatic model assessment of insulin resistance or 2-h plasma glucose after oral glucose tolerance test. Treatment effect was estimated according to mean difference in the changes from baseline of homeostatic model assessment of insulin resistance, 2-h oral glucose tolerance test plasma glucose, fasting plasma glucose and HbA1c between vitamin D and control groups. Meta-analysis of eligible studies was performed.

RESULTS

A total of 10 randomized controlled trials were included. Vitamin D did not significantly improve homeostatic model assessment of insulin resistance and 2-h oral glucose tolerance test plasma glucose: the mean differences were -0.06 (95% CI -0.36 to 0.24) and -0.23 mmol/l (95% CI -0.65 to 0.19), respectively. Subgroup analysis suggested that vitamin D improved homeostatic model assessment of insulin resistance in a subgroup with baseline 25-hydroxyvitamin D ≥ 50 nmol/l [mean difference -0.59 (95% CI -1.14 to -0.04); P = 0.03] and improved 2-h oral glucose tolerance test plasma glucose in the subgroup with baseline 25-hydroxyvitamin D < 50 nmol/l [mean difference -0.68 mmol/l (95% CI -1.35 to -0.01); P = 0.05]. Vitamin D significantly reduced fasting plasma glucose and HbA1c levels. The mean differences were -0.10 mmol/l (95% CI -0.18 to -0.03), P = 0.006 and -1 mmol/mol (95% CI -2 to 0), P = 0.008, respectively.

CONCLUSIONS

No beneficial effect of vitamin D in improving insulin resistance was identified.

The impact of vitamin D levels on glycemic control and bone mineral density in postmenopausal women with type 2 diabetes

OBJECTIVES

Whether glycemic control contributes to a decreased number of fractures or favorably impacts bone density in patients with type 2 diabetes mellitus (T2DM)has not been well established. Vitamin D (25 (OH) D3) deficiency appears to be related to glycemic control in patients with T2DM. The aim of this study was to determine the relationship between 25 (OH) D3 levels, glycemic control, bone mineral density (BMD), and the development of osteoporotic fractures (OPF) in postmenopausal women with T2DM.

METHODS

We reviewed the charts of 110 postmenopausal women diagnosed with T2DM. Glycosylated hemoglobin A1c (HbA1c) values over the previous 5 years were recorded and an average was obtained. Based on these values,the patients were divided into three groups: optimal,suboptimal, and poor control. Bone mineral density and 25(OH) D3 levels were also recorded.

RESULTS

In the group of patients with poorly controlled T2DM, 25 (OH) D3 levels were not significantly lower in comparison with the optimal control group 19.29 ± 7.70 vs 17.26 ± 6.93 (p = 0.53). No statistically significant linear relationship between HbA1c and 25 (OH) D3 levels( r(s) = −0.17, p = 0.06) was established. The frequency of osteoporosis and osteopenia was not significantly different between groups. The group with optimal glycemic control had an increased number of OPF events (p = 0.04).

CONCLUSIONS

We do not appreciate a significant relationship between 25 (OH) D3 levels and glucose control or OPF. Therefore, more studies are needed to identify the specific effect of 25 (OH) D3 in T2DM physiopathology.

Maternal vitamin D status as a critical determinant in gestational diabetes

OBJECTIVE

To synthesize published research to determine the evidence for the association between maternal vitamin D status during pregnancy and the development of gestational diabetes mellitus (GDM).

DATA SOURCES

Literature searches were conducted for data based articles that examined maternal vitamin D during pregnancy, GDM, glucose tolerance, and insulin resistance using the PubMed, CINAHL, and SCOPUS data bases and reference lists from reviewed papers.

STUDY SELECTION

Primary research studies published in the English language between 1999 and 2011 reporting findings regarding the association of vitamin D with glucose homeostasis during pregnancy and GDM.

DATA EXTRACTION

Study characteristics and findings related to vitamin D status determinants, gestational timing, and measures of glucose homeostasis and insulin resistance.

DATA SYNTHESIS

Six data based articles met the criteria for study inclusion. Study findings comprised solely Level-2 evidence for the association of maternal vitamin D deficiency and risk of GDM. The majority of studies (66%) were conducted between 24 and 30 weeks gestation. Five (83%) studies reported an inverse relationship between circulating vitamin D levels and markers of glucose homeostasis associated with gestational diabetes or an increased risk for GDM associated with reduced maternal levels of vitamin D. In one study, researchers did not identify an association between vitamin D and GDM but did identify an association between higher vitamin D levels and lower fasting glucose and insulin levels.

CONCLUSION

Maternal vitamin D deficiency and insufficiency is prevalent among gravid women and is associated with markers of altered glucose homeostasis. These findings underscore the need for mechanistic and clinical studies to determine optimal vitamin D status in pregnancy for reduction in the risk for GDM with implications for vitamin D supplementation as a potential target for GDM prevention.

Protean manifestations of vitamin D deficiency, part 2: deficiency and its association with autoimmune disease, cancer, infection, asthma, dermopathies, insulin resistance, and type 2 diabetes

Vitamin D deficiency is epidemic and its manifestations are protean. Vitamin D deficiency is associated with autoimmune diseases (particularly multiple sclerosis and type 1 diabetes) and has been associated with infection, allergy, asthma, and dermopathies (particularly psoriasis). Asthma may be worsened by vitamin D deficiency and correction of the deficiency has been shown to improve the manifestations of asthma. Vitamin D deficiency has been associated with multiple cancers, including those of the breast, colon, ovary, and prostate. Due mainly to increased insulin resistance but also to an impairment in insulin release, vitamin D deficiency is associated with the development of type 2 diabetes. In addition, the complications of diabetes may be worsened by vitamin D deficiency.

Daily consumption of vitamin D- or vitamin D + calcium-fortified yogurt drink improved glycemic control in patients with type 2 diabetes: a randomized clinical trial

BACKGROUND

Low serum concentrations of 25-hydroxyvitamin D [25(OH)D] have been associated with impaired glucose tolerance and diabetes.

OBJECTIVE

This study aimed to compare the effects of daily intake of vitamin D- or vitamin D(3) + calcium-fortified yogurt drink on glycemic status in subjects with type 2 diabetes (T2D).

DESIGN

Ninety diabetic subjects were randomly allocated to 3 groups to consume plain yogurt drink (PY; containing no vitamin D and 150 mg Ca/250 mL), vitamin D-fortified yogurt drink (DY; containing 500 IU vitamin D(3) and 150 mg Ca/250 mL), or vitamin D + calcium-fortified yogurt drink (DCY; containing 500 IU vitamin D(3) and 250 mg Ca/250 mL) twice per day for 12 wk. Fasting serum glucose (FSG), glycated hemoglobin (Hb A(1c)), homeostasis model assessment of insulin resistance (HOMA-IR), serum lipid profile, and percentage fat mass (FM) were assessed before (baseline) and after the intervention.

RESULTS

In both the DY and DCY groups, mean serum 25(OH)D(3) improved (+32.8 ± 28.4 and +28.8 ± 16.1 nmol/L, respectively; P < 0.001 for both), but FSG [-12.9 ± 33.7 mg/dL (P = 0.015) and -9.6 ± 46.9 mg/dL (P = 0.035)], Hb A(1c) [-0.4 ± 1.2% (P < 0.001) and -0.4 ± 1.9% (P < 0.001)], HOMA-IR [-0.6 ± 1.4 (P = 0.001) and -0.6 ± 3.2 (P < 0.001)], waist circumference (-3.6 ± 2.7 and -2.9 ± 3.3; P < 0.001 for both), and body mass index [in kg/m(2); -0.9 ± 0.6 (P < 0.001) and -0.4 ± 0.7 (P = 0.005)] decreased significantly more than in the PY group. An inverse correlation was observed between changes in serum 25(OH)D(3) and FSG (r = -0.208, P = 0.049), FM (r = -0.219, P = 0.038), and HOMA-IR (r = -0.219, P = 0.005).

CONCLUSION

Daily intake of a vitamin D-fortified yogurt drink, either with or without added calcium, improved glycemic status in T2D patients. This trial was registered at clinicaltrials.gov as NCT01229891.