***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Aims /hypothesisLow 25-hydroxyvitamin D levels predict future cardiovascular events and are common in patients with type 2 diabetes . We compared the effect of 100,000 and 200,000 IU doses of vitamin D3 on endothelial function , blood pressure and markers of glycaemic control in patients with type 2 diabetes . Methods This was a r and omised , parallel group , placebo-controlled trial . Patients with type 2 diabetes and baseline 25-hydroxyvitamin D levels < 100 nmol/l were enrolled from community and hospital-based diabetes clinics . Participants were assessed in a university department of clinical pharmacology and received a single oral dose of placebo or vitamin D3 ( 100,000 IU or 200,000 IU ) at baseline , r and omly allocated via numbered bottles prepared offsite ; participants and investigators were both blinded to treatment allocation . Endothelial function , office blood pressure , B-type natriuretic peptide , insulin resistance and glycosylated haemoglobin were measured at baseline , and at 8 and 16 weeks . Results We r and omised 61 participants to the three groups ( placebo 22 , 100,000 IU vitamin D3 19 , 200,000 IU vitamin D3 20 ) . There was no significant difference in the primary outcome of endothelial function at 8 weeks ( placebo 5.2 % , n = 22 ; 100,000 IU 4.3 % , n = 19 ; 200,000 IU 4.9 % , n = 17 ) or at 16 weeks . Insulin resistance and glycosylated haemoglobin did not improve with either dose of vitamin D3 . On covariate analysis , systolic blood pressure was significantly lower in both treatment arms than in the placebo group at 8 weeks ( placebo 146.4 mmHg , 100,000 IU 141.4 mmHg [ p = 0.04 vs placebo ] , 200,000 IU 136.8 mmHg [ p = 0.03 vs placebo ] ) . B-type natriuretic peptide levels were significantly lower in the 200,000 IU group by 16 weeks ( placebo 34 pg/ml , 200,000 IU 21 pg/ml , p = 0.02 ) . No significant excess of adverse effects was noted in the treatment arms . Conclusions /interpretationHigh-dose vitamin D3 improved systolic blood pressure and B-type natriuretic peptide levels , but not endothelial function , insulin resistance or glycosylated haemoglobin in patients with type 2 diabetes . Trial registration IS RCT N50587697 ( www.controlled-trials.com ) Funding Diabetes UK , grant number 06/0003429 . M. D. Witham is funded by a Scottish Government NES/CSO Clinician Scientist Award BACKGROUND Adequate calcium intake can have a favorable effect on some metabolic variables . OBJECTIVE The objective of the study was to determine the effects of daily calcium intake and of supplementation with calcium and vitamin D ( calcium+D ) during a weight-loss intervention on blood pressures , plasma lipid and lipoprotein concentrations , and glucose and insulin concentrations in low calcium consumers . DESIGN Healthy , overweight or obese women ( n = 63 ) with a daily calcium intake of < 800 mg/d were r and omly assigned in a double-blind manner to 1 of 2 groups : the group consuming 2 tablets/d of a calcium + vitamin D supplement ( 600 mg elemental calcium and 200 IU vitamin D/tablet ) or the group consuming placebo ; both groups observed a 700 kcal/d energy restriction . These 63 women then completed a 15-wk weight-loss intervention . RESULTS Initial daily calcium intake was significantly correlated with plasma HDL cholesterol ( r = 0.41 , P < 0.001 ) and with 2-h postload glycemia ( r = -0.29 , P < 0.05 ) during an oral-glucose-tolerance test , independent of fat mass and waist circumference . After the 15-wk intervention , significantly greater decreases in total : LDL and LDL : HDL ( P < 0.01 for both ) and of LDL cholesterol ( P < 0.05 ) were observed in the calcium+D group than in the placebo group . The differences in total : HDL and LDL : HDL were independent of changes in fat mass and in waist circumference . A tendency for more beneficial changes in HDL cholesterol , triacylglycerol , and total cholesterol was also observed in the calcium+D group ( P = 0.08 ) . CONCLUSION Consumption of calcium+D during a weight-loss intervention enhanced the beneficial effect of body weight loss on the lipid and lipoprotein profile in overweight or obese women with usual low daily calcium intake BACKGROUND Indirect evidence suggests that optimal vitamin D status is achieved with a serum 25-hydroxyvitamin D [ 25(OH)D ] concentration > 75 nmol/L. OBJECTIVE We aim ed to determine the intake of vitamin D(3 ) needed to raise serum 25(OH)D to > 75 nmol/L. DESIGN The design was a 6-mo , prospect i ve , r and omized , double-blinded , double-dummy , placebo-controlled study of vitamin D(3 ) supplementation .  Serum 25(OH)D was measured by  radioimmunoassay . Vitamin D(3 ) intake was adjusted every 2 mo by use of an algorithm based on serum 25(OH)D concentration . RESULTS A total of 138 subjects entered the study . After 2 dose adjustments , almost all active subjects attained concentrations of 25(OH)D > 75 nmol/L , and no subjects exceeded 220 nmol/L. The mean ( + /-SD ) slope at 9 wk [ defined as 25(OH)D change/baseline dose ] was 0.66 + /- 0.35 (nmol/L)/(microg/d ) and did not differ statistically between blacks and whites . The mean daily dose was 86 microg ( 3440 IU ) . The use of computer simulations to obtain the most participants within the range of 75 - 220 nmol/L predicted an optimal daily dose of 115 microg/d ( 4600 IU ) . No hypercalcemia or hypercalciuria was observed . CONCLUSIONS Determination of the intake required to attain serum 25(OH)D concentrations > 75 nmol/L must consider the wide variability in the dose-response curve and basal 25(OH)D concentrations . Projection of the dose-response curves observed in this convenience sample onto the population of the third National Health and Nutrition Examination Survey suggests a dose of 95 microg/d ( 3800 IU ) for those above a 25(OH)D threshold of 55 nmol/L and a dose of 125 microg/d ( 5000 IU ) for those below that threshold Vitamin D has been shown to increase insulin release from pancreatic islet cells in vitro , and to improve insulin secretion in vitamin D-deficient animals . Few attempts have been made to evaluate this issue directly in humans . We studied 35 otherwise healthy diabetic subjects in the early spring at the seasonal nadir of 25-hydroxyvitamin D [ 25(OH)D ] concentrations ( mean 35 + /- 7 nmol/L ) .  Fasting glucose , insulin , C-peptide , and glucagon concentrations , and their responses to Sustacal stimulation were not related to indexes of mineral metabolism . In 20 subjects , a double-blinded , placebo-controlled , crossover trials of 1,25-dihydroxyvitamin D[1,25](OH)2D ] treatment ( 1 micrograms/d for 4 d ) had no effect on fasting or stimulated glucose , insulin , C-peptide , or glucagon concentrations . However , insulin and C-peptide responses to Sustacal after 1,25(OH)2D treatment were related to duration of diabetes ( r2 = 0.28 , P = 0.052 and r2 = 0.25 , P = 0.002 , respectively ) in that short duration correlated with improvement after 1,25(OH)2D treatment . Hence , vitamin D nutrition , or 1,25(OH)2D therapy , had no major effect on glucose homeostasis in non-insulin-dependent diabetes mellitus OBJECTIVE To evaluate vitamin D as a predictor of all-cause mortality , progression from normoalbuminuria to micro- or macroalbuminuria , and the development of background or proliferative retinopathy in patients with type 1 diabetes . RESEARCH DESIGN AND METHODS A prospect i ve observational follow-up study in which an inception cohort of type 1 diabetic patients was followed from onset of diabetes diagnosed between 1979 and 1984 .  Plasma vitamin D [ 25(OH)D3 ] levels  were determined by high performance liquid chromatography/t and em mass spectrometry in 227 patients before the patients developed microalbuminuria . Values equal to or below the 10 % percentile ( 15.5 nmol/L ) were considered severe vitamin D deficiency . RESULTS Median ( range ) vitamin D  was 44.6 ( 1.7–161.7 ) nmol/L.  Vitamin D level was not associated with age , sex , urinary albumin excretion rate ( UAER ) , or blood pressure . During follow-up , 44 ( 18 % ) patients died . In a Cox proportional hazards model , the hazard ratio for mortality in subjects with severe vitamin D deficiency was 2.7 ( 1.1–6.7 ) , P = 0.03 , after adjustment for UAER , HbA1c , and conventional cardiovascular risk factors ( age , sex , blood pressure , cholesterol , smoking ) . Of the 220 patients , 81 ( 37 % ) developed microalbuminuria and 27 ( 12 % ) of these progressed to macroalbuminuria . Furthermore , 192 ( 87 % ) patients developed background retinopathy , whereas 34 ( 15 % ) progressed to proliferative retinopathy . Severe vitamin D deficiency at baseline did not predict the development of these microvascular complications . CONCLUSIONS In patients with type 1 diabetes , severe vitamin D deficiency independently predicts all-cause mortality but not development of microvascular complications in the eye and kidney . Whether vitamin D substitution in type 1 diabetic patients can improve the prognosis remains to be investigated OBJECTIVE The purpose of this study was to prospect ively examine the association between vitamin D and calcium intake and risk of type 2 diabetes .  RESEARCH DESIGN AND METHODS In the Nurses ' Health Study , we followed 83,779 women who had no history of diabetes , cardiovascular disease , or cancer at baseline for the development of type 2 diabetes .  Vitamin D and calcium intake from diet and supplements was assessed every 2 - 4 years . During 20 years of follow-up , we documented 4,843 incident cases of type 2 diabetes . RESULTS After adjusting for multiple potential confounders , there was no association between total vitamin D intake and type 2 diabetes . However , the relative risk ( RR ) of type 2 diabetes was 0.87 ( 95 % CI 0.75 - 1.00 ; P for trend = 0.04 ) comparing the highest with the lowest category of vitamin D intake from supplements . The multivariate RRs of type 2 diabetes were 0.79 ( 0.70 - 0.90 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from all sources and 0.82 ( 0.72 - 0.92 ; P for trend < 0.001 ) comparing the highest with the lowest category of calcium intake from supplements . A combined daily intake of > 1,200 mg calcium and > 800 IU vitamin D was associated with a 33 % lower risk of type 2 diabetes with RR of 0.67 ( 0.49 - 0.90 ) compared with an intake of < 600 mg and 400 IU calcium and vitamin D , respectively . CONCLUSIONS The results of this large prospect i ve study suggest a potential beneficial role for both vitamin D and calcium intake in reducing the risk of type 2 diabetes BACKGROUND Previous in vitro and in vivo studies have demonstrated that vitamin D could prevent pancreatic beta-cell destruction and reduce the incidence of autoimmune diabetes . In children with type 1 diabetes , vitamin D treatment produces moderate protective effects on residual beta-cell function and has proven to be safe . Therefore , we hypothesized that vitamin D might have protective effects on beta-cell function in patients with latent autoimmune diabetes in adults ( LADA ) , a form of slowly 
    Output:
    
Combining all studies , no significant improvement was seen in fasting glucose , HbA(1c ) or insulin resistance in those treated with vitamin D compared with placebo .
No effect was seen on glycated haemoglobin in patients with diabetes and no differences were seen for any outcome in patients with normal fasting glucose .
Insufficient data were available to draw conclusions regarding micro- or macrovascular events ; two trials failed to show a reduction in new cases of diabetes in patients treated with vitamin D.  CONCLUSIONS There is currently insufficient evidence of beneficial effect to recommend vitamin D supplementation as a means of improving glycaemia or insulin resistance in patients with diabetes , normal fasting glucose or impaired glucose tolerance