Insulin resistance has no impact on ghrelin suppression in pregnancy

Ghrelin is reduced in various states of insulin resistance. The aim of this study was to examine the relationship between ghrelin and glucose metabolism during pregnancy - a natural insulin-resistant state - in women with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) or gestational diabetes mellitus (GDM) and potential changes 3 months after delivery. A total of 54 women, 37 pregnant and with various degrees of insulin resistance and 24 postpartum (PP, seven of them also studied during pregnancy) were studied. Ghrelin plasma concentrations at fasting and 60' following glucose loading (75 g-2 h-oral glucose tolerance test), area under the curve of plasma glucose (G-AUC(OGTT)) and insulin sensitivity [homeostatic model assessment (HOMA) and oral glucose sensitivity index (OGIS) indices, respectively] were determined. Both baseline and 60' ghrelin concentrations were to a comparable degree ( approximately by 65%) suppressed in NGT, IGT and GDM as compared to the PP group (the latter being indistinguishable from NGT regarding glucose tolerance and insulin sensitivity). In all women studied both during and after pregnancy, ghrelin levels rose from pregnancy to PP (mean increase 313.8%; P < 0.03). There was no correlation between baseline ghrelin and insulin sensitivity as estimated from both baseline (HOMA) and dynamic (OGTT:OGIS) glucose and insulin data. Ghrelin is substantially decreased during pregnancy, but glucose-induced ghrelin suppression is preserved at a lower level. There is apparently no relation to the degree of insulin resistance.     

Studying the relation between vitamin D deficiency and glycemic state among pregnant women with gestational diabetes

AimThis study was conducted to illustrate the relation between vitamin D deficiency and glycemic parameters.Materials and methodsThe study was carried out on 80 pregnant females who were attending obstetrics and gynecology out-patient clinic in el-Shatby hospital in Alexandria university, Egypt. They were divided into 2 groups: group 1 (n = 40) pregnant females diagnosed with gestational diabetes de novo at week 24–28 and group 2 (n = 40) pregnant females of the same age group who were not suffering from any glucose intolerance (control group). Each patient was subjected to detailed history taking, complete physical examination, One step 75 gm Oral glucose tolerance test, insulin, glycated hemoglobin(HbA1c),homeostatic model assessment of insulin resistance(HOMA-IR), 25 hydroxy-vitamin D, serum calcium, phosphorous and parathormone were assessed.ResultsA statistically significant higher fasting blood glucose (FBG), HbA1c%, fasting insulin and HOMA-IR was observed in patients with Gestational diabetes mellitus (GDM) versus control (p < 0.001). However, no significant difference was observed as regards Vitamin D levels in patients with GDM and control group. Among patients with GDM, vitamin D was found to correlate negatively with HbA1c (p < 0.001), insulin(p = 0.019) and HOMA-IR(p = 0.034).ConclusionNo definite causal relationship was observed between low vitamin D and subsequent occurrence of GDM.however, a significant correlation was found between the degree of vitamin D deficiency and the insulin resistance in patients with GDM.     

Serum 25-hydroxyvitamin D is associated with insulin resistance independently of obesity in children ages 5–17

AimTo determine the association of vitamin D with insulin resistance and obesity in children.MethodsA total of 92 obese and 58 non-obese children aged 5–17 years were evaluated. Data were collected related to anthropometric (weight, height), and biochemical parameters (fasting plasma glucose, serum insulin, serum 25-hydroxyvitamin D, lipid profile, vitamin B12, parathormone) and physical examination (blood pressure, acanthosis nigricans, stria, lipomastia). Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA). HOMA-IR = fasting insulin level (μU/ml) × fasting glucose (mg/dL)/405. A HOMA-IR value >2.5 was defined as insulin resistance.ResultsAccording to the US Endocrine Society classification, vitamin D deficiency (0−20 ng/ml) was determined at significantly higher rates in the obese group than in the control group (p < 0.001). The rate of subjects with a vitamin D level of 20−30 ng/ml was significantly lower in the obese group than in the control group (p < 0.001) Within the obese group a statistically significant difference was determined between the insulin resistant and non-insulin resistant groups in respect of serum 25-hydroxyvitamin D levels (p = 0.001) and vitamin B12 levels (p = 0.001). A significant negative correlation was determined between serum 25-hydroxyvitamin D and HOMA-IR (r=−0.256, p = 0.016) and insulin (r = −0.258, p = 0.015). The systolic blood pressure (p = 0.001) and diastolic blood pressure (p = 0.003) values were significantly different in the control and obese groups. A statistically significant difference was determined between the control and obese groups in terms of the levels of insulin, HOMA-IR, HbA1c, cortisol, LDL, total cholesterol, HDL, triglyceride, hemoglobin, MCV, MPV, and calcium.ConclusionThe prevalence of vitamin D deficiency was higher in obese children compared to normal-weight and overweight children. Serum 25(OH)D levels showed a negative correlation with insulin and HOMA-IR. Serum 25(OH)D is associated with insulin resistance independently of obesity.     

Pancreatic secretion in man with subclinical vitamin D deficiency

Summary The effects of subclinical vitamin D deficiency and vitamin D supplementation on oral glucose tolerance and secretion of pancreatic hormones were studied in 10 diphenyl-hydantoin-treated epileptic patients and 15 geriatric patients. Their mean serum concentrations of 25-hydroxyvitamin D₃ and 1,25-dihydroxyvitamin D₃ decreased markedly, but returned to normal within 2 weeks of oral supplementation with 25-hydroxyvitamin D₃. The serum concentration of ionized calcium was within the normal range before treatment, and remained unchanged. Serum parathyroid hormone was increased during vitamin D deficiency, but decreased significantly (p < 0.05) afterwards. In vitamin D-deficient epileptic and geriatric patients, the 2- and 3-h insulin levels after glucose ingestion were increased when compared with control values, and glucagon secretion was not suppressed by glucose. Oral glucose tolerance of both groups of patients did not change after 25-hydroxyvitamin D₃ supplementation. Insulin secretion remained unchanged in geriatric patients, but was reduced to normal values in epileptic patients. Glucagon suppressibility by glucose was partly restored after vitamin D supplementation in epileptic patients but not in geriatric patients. In contrast to that observed in severely vitamin D-deficient rats or rabbits, correction of subclinical vitamin D deficiency failed to enhance insulin secretion or to improve glucose tolerance in man.     

No relationship between vitamin D status and insulin resistance in a group of high school students

Objective: To investigate the effects of vitamin D deficiency on both insulin resistance and risk of metabolic syndrome in children. Methods: The study group consisted of 301 children and adolescents with a mean age of 14.2±1.8 years. Serum 25-hydroxyvitamin D [25(OH)D] levels and insulin resistance indices were evaluated. According to serum 25(OH)D levels, the subjects were classified in 3 groups. Those with levels ≤10 ng/mL were labeled as the vitamin D deficient group (group A), those with levels of 10-20 ng/mL as the vitamin D insufficient group (group B) and those with ≥20 ng/mL as having normal vitamin D levels (group C). Metabolic syndrome was defined according to the International Diabetes Federation consensus. The participants with and without metabolic syndrome were compared in terms of 25(OH)D levels.Results: Mean 25(OH)D level of the total group was 18.2±9.3 (2.8-72.0) ng/mL. Distribution of individuals according to their vitamin D levels showed that 11.6% were in group A, 53.5% in group B, and 34.9% in group C. The proportions of boys and girls in these categories were 22.9% and 77.1% in group A, 36.6% and 63.4% in group B, 54.3% and 45.7% in group C, respectively. There were no significant differences in 25(OH)D levels in the individuals with and without impaired fasting glucose or impaired glucose tolerance. No relationship was observed between insulin resistance/sensitivity indices and vitamin D status (p>0.05). Metabolic syndrome was diagnosed in 12.3% (n=37) of the children. There was also no difference in mean 25(OH)D levels between individuals who had and those who did not have the metabolic syndrome.Conclusion: In our study, no correlations were found between insulin measurements during oral glucose tolerance test and vitamin D deficiency. Nonetheless, more extended studies including vitamin D supplementation and evaluating insulin sensitivity via clamp technique are needed to further elucidate this relationship.Conflict of interest:None declared.     

Assessment of insulin sensitivity/resistance and their relations with leptin concentrations and anthropometric measures in a pregnant population with and without gestational diabetes mellitus

Fifty-six pregnant women with gestational diabetes mellitus (GDM) and 42 normal glucose tolerant (NGT) pregnant women between 26 and 36 gestational weeks were included in the study prospectively. The body fat percentage (BFP) was calculated using the Siri formula from skinfold thickness (SFT) measurements.Both groups were comparable for gestational age, height, weight, and body mass index (P>.05). Insulin resistance assessed by homeostasis model assessment for insulin resistance (HOMA-IR) method was significantly higher in GDM patients compared to their NGT weight-matched control group. In contrast, the insulin sensitivity calculated from quantitative insulin sensitivity check index (QUICKI-IS) equation was significantly lower in GDM group. Calculated lean body mass was found to be similar in between both groups. Body fat percentage derived from SFT parameters was significantly higher in women with GDM. Women with GDM had significantly higher levels of serum insulin and leptin concentrations when compared with the NGT group. All SFT measurements were higher in GDM group when compared to those in NGT women. We did not find any correlation between leptin levels and insulin resistance; we found negative correlation between leptin levels and insulin sensitivity. Thus, we observed that leptin may contribute development of GDM by decreasing insulin sensitivity but not increasing insulin resistance. Also, we observed that the BFP estimated by the Siri formula from SFT measurements correlated significantly with HOMA-IR and QUICKI-IS and leptin concentrations in pregnant women.We suggest that by simply evaluating SFT, we may hold a view about BFP and leptin concentrations and insulin sensitivity in pregnant women.     

Differences in homeostatic model assessment (HOMA) values and insulin levels after vitamin D supplementation in healthy men: a double‐blind randomized controlled trial

Vitamin D is thought to play a role in glucose metabolism. The aim of the present study was to determine the effect of vitamin D supplementation on markers of insulin sensitivity and inflammation in men without diabetes with vitamin D deficiency/insufficiency. In this 1‐year double‐blind randomized controlled trial, 130 men aged 20–65 years (mean age 47.52 ± 11.84 years) with serum 25‐hydroxyvitamin D levels <50 nmol/l (mean 38.89 ± 8.64 nmol/l) were randomized to treatment (100 000 IU vitamin D bimonthly) or placebo. Anthropometric measurements, demographic questionnaires, and blood indices (fasting glucose, insulin, high‐sensitivity C‐reactive protein, lipids) were collected and repeated after 6 and 12 months. The compliance rate was 98.5%. Multivariate models, adjusted for baseline levels, age, body mass index, sun exposure, physical activity and LDL, showed significant differences in insulin and homeostatic model assessment of insulin resistance (HOMA‐IR) values between groups. Levels of insulin and HOMA‐IR values remained steady during the study period in the treatment group but increased by 16% in the control group (p = 0.038 and p = 0.048, respectively). Vitamin D supplementation administered for 12 months in healthy men maintained insulin levels and HOMA‐IR values relative to the increase in the control group. Further studies are needed to establish the long‐term effect of vitamin D supplementation on the risk of diabetes.     

Prevalence of gestational diabetes mellitus and the effect of weight on measures of insulin secretion and insulin resistance in third‐trimester pregnant rural women residing in the Central Region of Limpopo Province,South Africa

Aims To examine the prevalence of gestational diabetes in third‐trimester pregnant women as well as to assess their insulin secretion and insulin resistance (IR). Methods Third‐trimester pregnant women (n = 262) attending antenatal care at local clinics in the central region of the Limpopo Province underwent a 2‐h oral glucose tolerance test (OGTT) with blood collected at 0, 30 and 120 min. Glucose and insulin were measured. Results The prevalence of gestational impaired glucose tolerance (GIGT) and gestational diabetes mellitus (GDM) was 8.8% (7.3% GIGT; 1.5% GDM). Women with GIGT/GDM were significantly older and had more children compared with women with a normal response to the OGTT. Homeostasis model assessment (HOMA)‐IR and fasting insulin were lower in the GIGT/GDM group compared with the normal group, as were measures of insulin secretion (HOMA B‐cell function and insulinogenic index). Furthermore, women with body mass index (BMI) ≥ 30.0 kg/m² were significantly older and had higher parity, systolic and diastolic blood pressure measurements than those with BMI 25.0–29.9 kg/m² and BMI < 25.0 kg/m². However, increased BMI was not associated with an increased risk of GIGT/GDM. Conclusion The present study shows that there is a high prevalence of GIGT/GDM, with most women having IGT. The GIGT/GDM present in these women is characterized by increased insulin sensitivity accompanied by reduced pancreatic B‐cell function. Additionally, heavier women appear to have increased first phase insulin secretion, suggesting the presence of insulin resistance.     

Relationship between fasting serum glucose, age, body mass index and serum 25 hydroxyvitamin D in postmenopausal women

OBJECTIVE: Because it has been reported that vitamin D, given to mother or infant, can prevent type I diabetes in children, that diabetes is more common in adults with low serum vitamin D and that insulin secretion and action are related to vitamin D levels in healthy young adults we examined the relationship between serum vitamin D metabolites and fasting serum glucose in patients attending our outpatient clinics. DESIGN: Retrospective examination of convenience sample of postmenopausal women attending our osteoporosis clinics. PATIENTS: A total of 753 postmenopausal women attending a university hospital outpatient clinic and not on any treatment known to affect glucose metabolism. MEASUREMENTS: Body weight and height, serum 25-hydroxyvitamin D [25(OH)D], serum 1,25-dihydroxyvitamin D [1,25(OH)2D], serum PTH and fasting serum glucose. RESULTS: On simple correlation fasting serum glucose was a positive function of age (P < 0.05), weight (P < 0.001) and body mass index (BMI) (P < 0.001) and a negative function of serum 25(OH)D (P < 0.001), but it was not significantly related to either serum 1,25(OH)2D, PTH or creatinine. When fasting serum glucose was regressed simultaneously on age, BMI and 25(OH)D, glucose was still an inverse function of 25(OH)D (P = 0.006). CONCLUSIONS: Fasting serum glucose increased as 25(OH)D levels fell throughout the range of serum 25(OH)D measured but the greatest increase was observed in those with 25(OH)D below 40 nmol/l.     

Lower vitamin D levels at first trimester are associated with higher risk of developing gestational diabetes mellitus

The progressive increase of insulin resistance observed in pregnancy contributes to the pathophysiology of gestational diabetes mellitus (GDM). There is controversy whether vitamin D deficiency contributes to abnormal glycemic regulation in pregnancy. We tested the associations between first trimester 25-hydroxyvitamin D (25OHD) levels and: 1) the risk of developing GDM; 2) insulin resistance/sensitivity, beta cell function and compensation indices in a large population-based prospective cohort of pregnant women. Participants (n = 655) were seen at first (6–13 weeks) and second (24–28 weeks) trimesters for blood samples. At first trimester, 25OHD levels were measured. At second trimester, glucose and insulin were measured 3 times during the oral glucose tolerance test to estimate insulin resistance (HOMA-IR), beta cell function (HOMA-B), insulin sensitivity (Matsuda index), insulin secretion (AUC_ins/gluc) and beta cell compensation (ISSI-2). Based on IADPSG criteria, 54 participants (8.2 %) developed GDM. Lower first trimester 25OHD levels were associated with higher risk of developing GDM even after adjustment for vitamin D confounding factors and GDM risk factors (OR = 1.48 per decrease of one SD in 25OHD levels; P = 0.04). Lower first trimester 25OHD levels were associated with higher HOMA-IR (r = ? 0.08; P = 0.03), lower Matsuda index (r = 0.13; P = 0.001) and lower ISSI-2 (r = 0.08; P = 0.04). After adjustment for confounders, we found no significant association with HOMA-B and AUC_ins/gluc. Our results suggest that low levels of 25OHD at first trimester are (1) an independent risk factor for developing GDM and (2) associated with insulin resistance at second trimester.     

Serum homocysteine levels are increased in women with gestational diabetes mellitus

Serum homocysteine (sHcy) has been found to be elevated in patients with type 2 diabetes mellitus, as well as in other clinical conditions associated with insulin resistance and/or vascular diseases. The aims of this study were to measure the relationship between sHcy with biohumoral markers of insulin resistance in pregnant women affected with gestational diabetes mellitus (GDM). We studied 2 groups of pregnant women categorized, after a 100-g, 3-hour oral glucose tolerance test (OGTT) as nondiabetic (n = 78) or affected with GDM (n = 15), by measuring sHcy, serum folate, albumin, vitamin B(12), uric acid, and lipids. In both groups, peripheral insulin sensitivity was measured by using the OGTT-derived index of Matsuda and DeFronzo (ISI(OGTT)). Serum homocysteine was significantly higher in the group with GDM compared with nondiabetic women (5.88 +/- 2.26 micromol/L v 4.45 +/- 1.52 micromol/L; P =.003); was inversely related to serum folate (r = -.48; P =.0001), and was significantly related to serum albumin (r =.27; P =.009), 2-hour plasma glucose (r =.25; P =.01), as well as to serum uric acid (r =.23; P =.03). No relationship was observed between sHcy and serum vitamin B(12), serum triglycerides, total, or high-density lipoprotein (HDL) cholesterol, mean blood pressure and ISI(OGTT). Vitamin B(12) was correlated with ISI(OGTT) (r =.36; P =.0005) and inversely with mean blood pressure (r = -.24; P =.02). GDM remained significantly associated with higher sHcy concentrations also after adjusting for age, serum folate, albumin, uric acid, ISI(OGTT), and vitamin B(12) (P =.006). In conclusion, we found that sHcy is significantly increased in women with GDM, independently of other confounding variables, is significantly related to 2-hour OGTT plasma glucose, and seems unrelated to insulin resistance in these subjects.     

A relationship between serum ferritin and the insulin resistance syndrome is present in non-diabetic women but not in non-diabetic men

BACKGROUND: Previous studies have suggested that serum ferritin is one of the components of the insulin resistance syndrome in Caucasians. Because serum ferritin levels differ significantly between men and women, variation in the role of ferritin in insulin resistance between the sexes, particularly in Asian populations, is still unknown. OBJECTIVE: To examine whether the association between serum ferritin and insulin resistance differs between men and women in randomly selected non-diabetic Chinese subjects. DESIGN: A retrospective study. PATIENTS: Four hundred and seventeen non-diabetic Chinese subjects (140 men and 277 women) were studied. MEASUREMENTS: Fasting plasma glucose, insulin, lipoproteins and serum ferritin concentrations, as well as plasma glucose and insulin responses to a 75-g oral glucose test (n = 219), were determined. RESULTS: Fasting serum ferritin concentrations (mean +/- SEM) were significantly higher in men than in women (504 +/- 33 vs. 242 +/- 18 pmol/l, P < 0.001). In women, fasting serum ferritin concentrations correlated significantly with age, body mass index (BMI), amount of body fat, fasting plasma glucose, insulin, cholesterol, triglyceride concentrations, glucose response to an oral glucose load, and homeostasis model assessment (HOMA) of insulin resistance but not with blood pressure, high density lipoprotein (HDL) cholesterol levels and insulin response to oral glucose. On the contrary, none of the above anthropometric and metabolic variables was related to fasting serum ferritin levels in men. HOMA insulin resistance increased progressively across three different tertiles for measured serum ferritin concentrations in women (P < 0.003). In men, HOMA insulin resistance levels were not different among three differing measured serum ferritin levels (P = 0.424). Adjustment for age, BMI and menopause status did not change the significant relationship between HOMA insulin resistance and serum ferritin in women. CONCLUSIONS: We observed that a relationship between serum ferritin levels and insulin resistance exists in women but not in men. This sexual dimorphism merits further investigation.     

Influence of vitamin D status on insulin secretion and glucose tolerance in the rabbit

The influence of vitamin D status on insulin secretion and glucose tolerance was studied by a longitudinal design in the rabbit. Intravenous glucose tolerance tests were performed in Dutch rabbits (n = 12) before and after nutritional vitamin D deficiency, characterized by an absence of circulating 25-hydroxyvitamin D3, a 50% decrease in 1,25-dihydroxyvitamin D3, and a 16% decrease in serum calcium concentrations. Glucose-induced insulin secretion was reduced by 41% as early as 2 months after the start of the vitamin D-deficient diet and was associated with an impairment of glucose tolerance. An iv calcium infusion restored the serum calcium concentration of the vitamin D-deficient rabbits (n = 5), but did not improve glucose-mediated insulin secretion. When these animals received a single ip injection of 100 ng 1,25-dihydroxyvitamin D3 10 h before the glucose test, their insulin responses significantly increased. Supplementation with 25-hydroxyvitamin D3 for 2 weeks in another group of rabbits (n = 4) resulted in marked improvement in glucose-stimulated insulin release and glucose tolerance. These results show that vitamin D affects glucose-induced insulin secretion by a mechanism that involves more than its regulating action on serum calcium concentration.     

Low serum 25-hydroxyvitamin D concentrations are associated with insulin resistance and obesity in women with polycystic ovary syndrome.

Insulin resistance (IR) and central obesity are common features of the polycystic ovary syndrome (PCOS). Vitamin D is thought to play a role in the pathogenesis of type 2 diabetes by affecting insulin metabolism. The aim of our study was to investigate the effect of 25-hydroxyvitamin D (25-OH-VD) on metabolic parameters and IR in PCOS. In 120 untreated PCOS patients (median age 28 years) levels of 25-OH-VD (radioimmunoassay method provided by DiaSorin), calcium and anorganic phosphate were measured. In addition, endocrine and metabolic variables were evaluated and a glucose tolerance test was performed to assess indices of IR. In the entire PCOS cohort, 25-OH-VD concentrations were negatively correlated with body mass index (r=-0.2765), body fat (r=-0.2490), HOMA-IR (r=-0.1947), hyperinsulinemia (r=-0.1892) and leptin levels (r=-0.2834), and positively correlated with HDL cholesterol (r=0.2630) (all p<0.05). Subgroup analysis of lean, overweight and obese women revealed significant higher 25-OH-VD levels in lean women. Differences remained significant when women were divided according to their 25-OH-VD levels. Women with hypovitaminosis D (<9 ng/ml) had higher mean BMI, indices of IR and leptin levels compared to women with normal serum levels (all p<0.05). Analysis of vitamin D and biochemical endocrine PCOS features revealed a significant correlation only between 25-OH-VD and sex hormone-binding globulin as well as the free androgen index. In conclusion, in PCOS women, low 25-OH-VD levels are associated with obesity and insulin resistance but not with PCOS per se.     

Determination of insulin resistance using the homeostatic model assessment (HOMA) and its relation with the risk of developing pregnancy-induced hypertension

OBJECTIVE: To assess whether increased insulin resistance determined by homeostatic model assessment (HOMA) early in pregnancy is associated with the subsequent development of pregnancy-induced hypertension (PIH) in Colombian women with known risk factors. METHODS: We conducted a nested case control study in a prospective cohort of 572 normotensive pregnant women, with gestational age < or = 30 weeks, recruited in Bucaramanga and Floridablanca, Colombia. Fasting plasma glucose and insulin concentrations were determined at enrollment, and HOMA index was calculated. Log-transformed HOMA (log-HOMA) was used in the statistical analysis. Thirty nine PIH cases (18 preeclampsia [PE], 21 gestational hypertension [GH]) were compared to 78 controls, matched by body mass index, gestational and maternal age at enrollment. RESULTS: Women who subsequently developed PIH had higher levels of log-HOMA at enrollment (-0.13 +/- 0.54 v 0.21 +/- 0.60; P = .002), which was significantly associated with the development of PIH (odds ratio 3.13, 95% confidence interval 1.41-6.94; P = .005). Higher log-HOMA was found in women who subsequently developed PE (0.28 +/- 0.58; P = .003), and in those who presented with GH (0.15 +/- 0.62; P = .026). CONCLUSIONS: Women who subsequently develop PIH have a higher degree of insulin resistance determined by log-HOMA early in pregnancy, before the onset of clinical manifestations of the disease. The HOMA seems to be a useful method to evaluate women at risk of developing PIH. More studies are required to confirm its usefulness as a screening tool to identify pregnant women at risk of developing PIH.     

Lack of effect of subtherapeutic vitamin D treatment on glycemic and lipid parameters in Type 2 diabetes: A pilot prospective randomized trial

Background: Epidemiological studies suggest a higher prevalence of metabolic syndrome and its components among individuals with vitamin D deficiency. The aim of the present study was to determine whether vitamin D treatment improves glucose control and insulin sensitivity in Type 2 diabetes mellitus (T2DM). Methods: Subjects with T2DM and serum 25‐hydroxyvitamin D (25(OH)D) concentrations <25 ng/mL were randomized to receive 400 IU (Group 1) or 1200 IU (Group 2) cholecalciferol for 4 months. Fasting plasma glucose, glycosylated hemoglobin (HbA1c), Quantitative Insulin Sensitivity Check Index (QUICKI), serum lipid levels and serum adiponectin were measured at baseline and at 4 months. Results: Mean 25(OH)D levels increased in both groups (from 17.6 ± 1.5 to 25.5 ± 1.8 ng/mL in Group 1 and from 15.6 ± 1.4 to 27.4 ± 2.4 ng/mL in Group 2; P ≤ 0.001 vs baseline for each group). No significant differences were noted in fasting plasma glucose, HbA1c, QUICKI, serum adiponectin, and lipid levels compared with baseline within groups or between the two groups. Conclusions: In the present pilot study, conventional vitamin D treatment at a level improving, but not optimizing, serum 25(OH)D did not improve glycemia, insulin sensitivity, or lipid profile. However, diabetes and lipids were relatively well controlled at baseline. Future studies should be designed to achieve optimal concentrations of serum 25(OH)D (at least >32 ng/mL) and should include subjects showing more abnormal parameters of glycemia, lipid, and insulin sensitivity at baseline.     

Vitamin D deficiency is common and associated with metabolic risk factors in patients with polycystic ovary syndrome

Both vitamin D deficiency and polycystic ovary syndrome (PCOS) are associated with aspects of metabolic syndrome, but it is unclear whether vitamin D deficiency contributes to the metabolic disturbances commonly found in women with PCOS. This study sought to investigate (1) the prevalence of vitamin D deficiency in PCOS women in Scotland and (2) the relationship between vitamin D status and metabolic risk factors. This was an observational study on 52 women (25 in PCOS group and 27 in control group). Serum 25-hydroxyvitamin D concentrations less than 25 nmol/L were classified as severe vitamin D deficiency and were found in 44.0% and 11.2% of subjects in the PCOS and control groups, respectively (P = .047). Among the PCOS subjects, 25-hydroxyvitamin D concentrations were negatively correlated with body mass index (P = .033), C-reactive protein (P = .027), and free androgen index (P = .025) and positively correlated with quantitative insulin sensitivity check index (P = .035), high-density lipoprotein cholesterol (HDL-C) (P = .033), and sex hormone binding globulin (P = .038). Associations of vitamin D deficiency with quantitative insulin sensitivity check index and HDL-C were independent of body mass index and waist-to-hip ratio. Vitamin D deficiency is highly prevalent in PCOS women in Scotland, and a larger proportion of PCOS patients than control women were found to be vitamin D deficient. We also demonstrate correlations of vitamin D status with insulin sensitivity, HDL-C, and C-reactive protein in PCOS patients, which support the increasing evidence that vitamin D deficiency is associated with multiple metabolic risk factors in PCOS women.     

Mannose-binding lectin gene polymorphisms are associated with gestational diabetes mellitus

Insulin resistance is a feature of gestational diabetes mellitus (GDM). Inverse correlations between indexes of insulin sensitivity and serum markers of inflammation have been observed and, particularly, TNF-alpha has been shown to be associated with the appearance of insulin resistance in pregnancy. Mannose-binding lectin (MBL) is a protein member of the collectin family. Its deficiency is genetically determined and predisposes to recurrent infections and chronic inflammatory diseases. To test the hypothesis that a genetic predisposition to a proinflammatory state could favor the appearance of GDM during pregnancy, we studied R52C and G54D polymorphisms of MBL2 gene and plasma MBL levels from 105 consecutive GDM women and 173 healthy pregnant women. An association was found between G54D and GDM [odds ratio, 2.03 (1.18-3.49); P < 0.01], and this association remained significant when the presence of both mutated alleles was considered [odds ratio, 1.76 (1.04-2.96); P < 0.05] but not for the R52C. GDM patients who carried the G54D mutation required insulin therapy more frequently (56.4 vs. 30.4%, chi(2) =5.83; P = 0.027) and had heavier infants (3326.4 +/- 546.9 vs. 3087.5 +/- 395.5 g; P < 0.05) than GDM women homozygous for the wild-type allele. An inverse correlation in GDM patients between neonatal weight and plasma MBL levels (r = -0.320; P = 0.002) was found, remaining significant after adjustment for confounding variables. In conclusion, pregnant women bearing the G54D MBL allele have a greater risk for developing GDM and having heavier infants.     

Vitamin D: role in pregnancy and early childhood

Several studies in pregnant women and early childhood suggest that vitamin D deficiency (serum 25-hydroxyvitamin D levels <50 nmol/l) is common in both population groups. Recent recommendations have therefore reviewed the literature regarding the role of vitamin D in pregnant women and in early childhood. The Institute of Medicine, in their most recent assessment in 2010, recommended 600 IU per day in pregnant and lactating women. In 2011, the US Endocrine Task Force on Vitamin D commented that 600 IU per day may not be sufficient to correct vitamin D deficiency in pregnant and lactating women. Their recommendation was 1,500-2,000 IU vitamin D per day in pregnant and lactating women with vitamin D deficiency. For infants, the recommendation from both societies is consistently 400 IU vitamin D per day, and also in children both societies recommend 600 IU vitamin D per day. This review will summarize the scientific basis that led to the most recent recommendations.     

Effect of vitamin D on insulin sensitivity in elderly patients with impaired fasting glucose

Aim: Recent data has shown that vitamin D increases insulin sensitivity; however, there is little evidence about the effects of this treatment on elderly people with impaired fasting glucose. The aim of the present study was to investigate the effect of vitamin D treatment on insulin sensitivity and metabolic parameters in elderly people with impaired fasting glucose. Methods: A total of 28 elderly patients were enrolled into the vitamin D treatment group. The control group included 23 age‐, sex‐ and body mass index‐matched elderly participants. The vitamin D treatment group was treated with vitamin D₃ according to serum concentrations of 25(OH)D. Results: With supplementation, 96.0% of patients achieved a mean serum 25(OH)D concentration of 123.2 ± 59.9 nmol/L. After 4.7 ± 2.5 months of treatment, there was a significant decrease in homeostasis model assessment of insulin resistance, insulin and glucose concentrations in the vitamin D treatment group (P = 0.007, P = 0.007, P = 0.037, respectively). Vitamin D treatment significantly increased high‐density lipoprotein cholesterol (P = 0.037), but did not cause statistically significant differences in other lipid parameters. Conclusion: We found that vitamin D treatment might modify insulin sensitivity in the elderly with impaired fasting glucose. Geriatr Gerontol Int 2012; 12: 454–460.