Background: Vitamin D deficiency is associated with indicators of pre-diabetes including, insulin resistance, β-cell dysfunction and elevated plasma glucose with controversial findings from current trials. This study aims to investigate the long-term effect of vitamin D on glucose metabolism and insulin sensitivity in pre-diabetic and highly vitamindeficient subjects. Methods: One hundred thirty-two participants were randomized to 30,000 IU vitamin D weekly for 6 months. Participants underwent oral glucose tolerance test (OGTT) at 3-month intervals to determine the change in plasma glucose concentration at 2 h after 75 g OGTT (2hPCG). Secondary measurements included glycated hemoglobin, fasting plasma glucose and insulin, post-prandial insulin, indices of insulin sensitivity (HOMA-IR, Matsuda Index), β-cell function (HOMA-β, glucose and insulin area under the curve (AUC), disposition and insulinogenic indices), and lipid profile. Results: A total of 57 (vitamin D) and 75 (placebo) subjects completed the study. Mean baseline serum 25(OH) D levels were 17.0 ng/ml and 14.9 ng/ml for placebo and vitamin D group, respectively. No significant differences were observed for 2hPC glucose or insulin sensitivity indices between groups. HOMA-β significantly decreased in the vitamin D group, while area under curve for glucose and insulin showed a significant reduction in β-cell function in both groups. Additionally, HOMA-β was found to be significantly different between control and treatment group and significance persisted after adjusting for confounding factors. Conclusion: Vitamin D supplementation in a pre-diabetic and severely vitamin-deficient population had no effect on glucose tolerance or insulin sensitivity. The observed reduction in β-cell function in both placebo and vitamin D groups could be attributed to factors other than supplementation. Trial registration: NCT02098980, 28/03/2014 (www.clinicaltrials.gov).

Smoking self-efficacy, described as confidence in one’s ability to abstain from smoking in high-risk situations is a key predictor in cessation outcomes; however, there is a dearth of research on factors that influence self-efficacy surrounding smoking behavior. This study examines factors associated with baseline self-efficacy among treatment seeking participants enrolled in a pilot feasibility smoking cessation study. Participants (n = 247) were daily male smokers, residents of Doha in Qatar (18–60 years) who were enrolled in a telephone-based smoking cessation study. Baseline assessments included self-efficacy, home smoking rules, socio-demographic variables, smoking history, and psychosocial characteristics. Factors associated with self-efficacy were assessed using multiple linear regression analysis. Results showed that after controlling for relevant variables, number of cigarettes smoked (β^ = -0.22; 95% CI: -0.37, -0.06), having at least one quit attempt in the past year (β^ = 2.30; 95% CI: 0.27, 4.35), and reporting a complete home smoking ban (β^ = 3.13; 95% CI: 0.56, 5.70) were significantly associated with higher self-efficacy to quit smoking. These results provide data-driven indication of several key variables that can be targeted to increase smoking self-efficacy in this understudied population.

In Qatar, tobacco is the leading preventable cause of death and disease. Telephone-based interventions for smoking are cost-effective and scalable interventions that are effective in promoting smoking behavior change. While many countries have implemented these services within their tobacco control programs, there is a distinct dearth of a telephone-based smoking cessation intervention that is adapted and tailored to meet the needs of people who smoke in Qatar. This study presents the protocol of a primary health care center integrated smoking quitline program in Qatar. Participants will be recruited from seven smoking clinics (recruitment sites). Trained clinic staff will provide brief advice on quitting followed by a referral to the quitline. Eligible participants (male smokers over 18 years of age) will complete baseline questionnaires and receive five weekly proactive counseling calls, an end-of-treatment assessment (approx. 1 week after Session 5), and 1- and 3-month follow-up assessments. The main aim of this study is to assess the feasibility and acceptability, which include the recruitment and retention rate, compliance to pharmacotherapy, and participant satisfaction. This is the first study to integrate an evidence-based smoking cessation intervention delivered via telephone within the healthcare system in Qatar. If effective, results can inform the development of a large-scale telephone-based program that widely reaches users of tobacco in Qatar as well as in the Middle East.

Background: Vitamin D deficiency is associated with indicators of pre-diabetes including, insulin resistance, β-cell dysfunction and elevated plasma glucose with controversial findings from current trials. This study aims to investigate the long-term effect of vitamin D on glucose metabolism and insulin sensitivity in pre-diabetic and highly vitamin-deficient subjects. Methods: 132 participants were randomized to 30,000 IU vitamin D weekly for 6 months. Participants underwent oral glucose tolerance test (OGTT) at 3-month intervals to determine the change in plasma glucose concentration at 2h after 75g OGTT (2hPCG). Secondary measurements included glycated hemoglobin, fasting plasma glucose and insulin, post-prandial insulin, indices of insulin sensitivity (HOMA-IR, Matsuda Index), β-cell function (HOMA-β, glucose and insulin area under the curve (AUC), disposition and insulinogenic indices), and lipid profile. Results: A total of 57 (vitamin D) and 75 (placebo) subjects completed the study. Mean baseline serum 25(OH) D levels were 17.0 ng/ml and 14.9 ng/ml for placebo and vitamin D group, respectively. No significant differences were observed for 2hPC glucose or insulin sensitivity indices between groups. HOMA-β significantly decreased in the vitamin D group, while area under curve for glucose and insulin showed a significant reduction in β-cell function in both groups. Additionally, HOMA-β was found to be significantly different between control and treatment group and significance persisted after adjusting for confounding factors. Conclusion: Vitamin D supplementation in a pre-diabetic and severely vitamin-deficient population had no effect on glucose tolerance or insulin sensitivity. The observed reduction in β-cell function in both placebo and vitamin D groups could be attributed to factors other than supplementation. Trial registration: The trial was registered at www.clinicaltrials.gov with number: NCT02098980.

Background: Vitamin D deficiency is associated with indicators of pre-diabetes including, insulin resistance, β-cell dysfunction and elevated plasma glucose with controversial findings from current trials. This study aims to investigate the long-term effect of vitamin D on glucose metabolism and insulin sensitivity in pre-diabetic and highly vitamin-deficient subjects. Methods: 132 participants were randomized to 30,000 IU vitamin D weekly for 6 months. Participants underwent oral glucose tolerance test (OGTT) at 3-month intervals to determine the change in plasma glucose concentration at 2h after 75g OGTT (2hPCG). Secondary measurements included glycated hemoglobin, fasting plasma glucose and insulin, post-prandial insulin, indices of insulin sensitivity (HOMA-IR, Matsuda Index), β-cell function (HOMA-β, glucose and insulin area under the curve (AUC), disposition and insulinogenic indices), and lipid profile. Results: A total of 57 (vitamin D) and 75 (placebo) subjects completed the study. Mean baseline serum 25(OH) D levels were 17.0 ng/ml and 14.9 ng/ml for placebo and vitamin D group, respectively. No significant differences were observed for 2hPC glucose or insulin sensitivity indices between groups. HOMA-β significantly decreased in the vitamin D group, while area under curve for glucose and insulin showed a significant reduction in β-cell function in both groups. Additionally, HOMA-β was found to be significantly different between control and treatment group and significance persisted after adjusting for confounding factors. Conclusion: Vitamin D supplementation in a pre-diabetic and severely vitamin-deficient population had no effect on glucose tolerance or insulin sensitivity. The observed reduction in β-cell function in both placebo and vitamin D groups could be attributed to factors other than supplementation. Trial registration: The trial was registered at www.clinicaltrials.gov with number: NCT02098980.