Low vitamin K status in adults with cystic fibrosis is associated with reduced body mass index, insulin secretion, and increased pseudomonal colonization.

Patients with cystic fibrosis (CF) are at high risk of fat-soluble vitamin deficiencies, even with supplementation. The contribution of a suboptimal vitamin K status to respiratory and endocrine pathophysiology in CF has been inadequately characterized. This is a cross-sectional study in adult CF patients (≥18 years old) from the Montreal Cystic Fibrosis Cohort. Vitamin K1 (VK1) was measured with high-performance liquid chromatography, using fasted serum samples collected during an oral glucose tolerance test (OGTT: 2 h with plasma glucose and insulin every 30 min) (n = 168). Patients were categorized according to VK1 status (suboptimal defined as <0.30 nmol/L). Suboptimal VK1 levels were observed in 66% of patients. Patients with a suboptimal VK1 status have a higher risk of colonization with Pseudomonas aeruginosa (p = 0.001), have lower body mass index (BMI) (p = 0.003), and were more likely to have exocrine pancreatic insufficiency (p = 0.002). Using an established threshold for VK1, we did show significantly reduced OGTT-derived measures of insulin secretion in patients with a VK1 status below 0.30 nmol/L (first- and second-phase area under the curve (AUC)INS/GLU (p = 0.002 and p = 0.006), AUCINS (p = 0.012) and AUCINS/GLU (p = 0.004)). Subclinical vitamin K deficiency is more common than other fat-soluble vitamin deficiencies in patients with CF. We demonstrate an association between a suboptimal VK1 status and measures of insulin secretion. We highlight the potential associations of mild vitamin K deficiency with pseudomonal colonization and lower BMI, although these need to be validated in prospective studies.

Effect of vitamin D supplementation on oral glucose tolerance in individuals with low vitamin D status and increased risk for developing type 2 diabetes (EVIDENCE): A double-blind, randomized, placebo-controlled clinical trial.

AIMS: Low serum 25-hydroxyvitamin-D (25(OH)D) concentrations are associated with insulin resistance, ß-cell dysfunction and type 2 diabetes. We conducted a 24-week double-blind, randomized, placebo-controlled trial to examine the effect of 28 000 IU of vitamin D3 once weekly on plasma glucose after a 2 hour-75 g oral glucose tolerance test (2hrPC glucose), insulin sensitivity and ß-cell function. STUDY DESIGN AND METHODS: A total of 71 participants with serum 25(OH)D ≤65 nmol/L, impaired fasting glucose and elevated glycated hemoglobin were randomly assigned to receive 28 000 IU of vitamin D3 (VitD; n = 35) or placebo (n = 36) in cheese once weekly for 24 weeks. The primary outcome was the change in 2hPC glucose. Secondary outcomes were fasting glucose, fasting and postprandial insulin, indices of insulin sensitivity and ß-cell function, glycated hemoglobin and lipid profile. Participants underwent an oral glucose tolerance test to determine 2hPC glucose. RESULTS: Mean baseline serum 25(OH)D was 48.1 and 47.6 nmol/L in the VitD and placebo groups, respectively. Serum 25(OH)D significantly increased to 98.7 nmol/L (51 nmol/L increase; P < .0001) in the VitD group. No significant differences in fasting ( P = .42) or 2hPC glucose ( P = .55) or other indices of glucose metabolism, including ß-cell function and insulin sensitivity, were observed between groups. A subgroup analysis of individuals with 25(OH)D < 50 nmol/L and prediabetes did not change these results. The VitD group exhibited a significant reduction in LDL cholesterol (-0.27 vs 0.01 mmol/L, P = .03). CONCLUSION: Weekly doses of vitamin D3 in individuals with suboptimal vitamin D levels who were at risk for type 2 diabetes did not improve oral glucose tolerance or markers of glycaemic status.

Vitamin D3 supplementation among adult patients with cystic fibrosis.

BACKGROUND & AIMS: Vitamin D (Vit D) deficiency in cystic fibrosis (CF) is partially secondary to exocrine pancreatic insufficiency. Our aim was to establish a Vit D3 supplementation protocol that will increase 25(OH)D to the recommended level (30 ng/mL). METHODS: Retrospective study of 200 patients (≥18 years) conducted from February 2007 to June 2014 at the CF clinic of the Centre Hospitalier de l'Université de Montréal. Vit D3 supplementation protocol was 1600 IU/day or 10,000 IU/week during the summer (May 1st to October 31st) and 3200 IU/day or 20,000 IU/week during the winter (November 1st to April 30th), in addition to the 1200 IU/day included in multivitamins. RESULTS: Significant increase in serum 25(OH)D levels from baseline (25.9 ± 10.3 ng/mL) to follow-up (37.0 ± 11.4 ng/mL) (P ≤ 0.001). At follow-up, increased doses during the winter improved serum 25(OH)D levels to a degree comparable to the summer. CONCLUSIONS: This supplementation protocol is efficient and needs to be tested in other CF adult cohorts and correlated to potential health benefit measurements.

Association between post-dinner dietary intakes and nocturnal hypoglycemic risk in adult patients with type 1 diabetes.

AIMS: To describe (i) current bedtime nutritional practices and (ii) the association between post-dinner dietary intake and the occurrence of non-severe nocturnal hypoglycemia (NH) in real-life conditions among adult patients with type 1 diabetes using insulin analogs. METHODS: One hundred adults (median [interquartile range]: age 46.4 [36.0-55.8] years, HbA1c 7.9 [7.3-8.6] % (63 [56-70] mmol/mol)) using multiple daily injections (n=67) or insulin pump (n=33) wore a blinded continuous glucose monitoring system and completed a food diary for 72-h. RESULTS: NH occurred on 28% of 282 nights analyzed. (i) Patients reported post-dinner dietary intakes on 63% of the evenings. They injected rapid-acting insulin boluses on 64 occasions (23% of 282 evenings). These insulin boluses were mostly injected with (n=37) dietary intakes. (ii) Post-dinner dietary intake was not associated with NH occurrence in univariate analyses. In multivariate analyses, the injection of rapid-acting insulin modulated the association between post-dinner dietary intake and NH: with insulin, post-dinner carbohydrate intake was positively associated with NH (odds ratio (OR): 1.16 [95% confidence interval, CI: 1.04-1.29] per 5g increase, p=0.008); without insulin, post-dinner protein intake was inversely associated with NH occurrence (OR [95% CI]: 0.88 [0.78-1.00] per 2g increase, p=0.048). CONCLUSIONS: NH remains frequent in adults with type 1 diabetes. There is a complex relationship between post-dinner dietary intake and NH occurrence, including the significant role of nutrient content and rapid-acting insulin injection that requires further investigation.