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Vitamin D and Risk for Type 2 Diabetes in People With Prediabetes : A Systematic Review and Meta-analysis of Individual Participant Data From 3 Randomized Clinical Trials

Author/s: 
Pittas, A. G., Kawahara, T., Jorde, R., Dawson-Hughes, B., Vickery, E. M., Angellotti, E., Nelson, J., Trikalinos, T. A., Balk, E. M.

Background: The role of vitamin D in people who are at risk for type 2 diabetes remains unclear.

Purpose: To evaluate whether administration of vitamin D decreases risk for diabetes among people with prediabetes.

Data sources: PubMed, Embase, and ClinicalTrials.gov from database inception through 9 December 2022.

Study selection: Eligible trials that were specifically designed and conducted to test the effects of oral vitamin D versus placebo on new-onset diabetes in adults with prediabetes.

Data extraction: The primary outcome was time to event for new-onset diabetes. Secondary outcomes were regression to normal glucose regulation and adverse events. Prespecified analyses (both unadjusted and adjusted for key baseline variables) were conducted according to the intention-to-treat principle.

Data synthesis: Three randomized trials were included, which tested cholecalciferol, 20 000 IU (500 mcg) weekly; cholecalciferol, 4000 IU (100 mcg) daily; or eldecalcitol, 0.75 mcg daily, versus matching placebos. Trials were at low risk of bias. Vitamin D reduced risk for diabetes by 15% (hazard ratio, 0.85 [95% CI, 0.75 to 0.96]) in adjusted analyses, with a 3-year absolute risk reduction of 3.3% (CI, 0.6% to 6.0%). The effect of vitamin D did not differ in prespecified subgroups. Among participants assigned to the vitamin D group who maintained an intratrial mean serum 25-hydroxyvitamin D level of at least 125 nmol/L (≥50 ng/mL) compared with 50 to 74 nmol/L (20 to 29 ng/mL) during follow-up, cholecalciferol reduced risk for diabetes by 76% (hazard ratio, 0.24 [CI, 0.16 to 0.36]), with a 3-year absolute risk reduction of 18.1% (CI, 11.7% to 24.6%). Vitamin D increased the likelihood of regression to normal glucose regulation by 30% (rate ratio, 1.30 [CI, 1.16 to 1.46]). There was no evidence of difference in the rate ratios for adverse events (kidney stones: 1.17 [CI, 0.69 to 1.99]; hypercalcemia: 2.34 [CI, 0.83 to 6.66]; hypercalciuria: 1.65 [CI, 0.83 to 3.28]; death: 0.85 [CI, 0.31 to 2.36]).

Limitations: Studies of people with prediabetes do not apply to the general population. Trials may not have been powered for safety outcomes.

Conclusion: In adults with prediabetes, vitamin D was effective in decreasing risk for diabetes.

Primary funding source: None. (PROSPERO: CRD42020163522).

Keywords 
Kidney Cholecalciferol Intention to Treat Analysis type 2 diabetes Randomized Controlled Trials as Topic

Screening for Prediabetes and Type 2 Diabetes

Author/s: 
US Preventative Services task Force

IMPORTANCE An estimated 13% of all US adults (18 years or older) have diabetes, and 34.5%
meet criteria for prediabetes. The prevalences of prediabetes and diabetes are higher in older
adults. Estimates of the risk of progression from prediabetes to diabetes vary widely, perhaps
because of differences in the definition of prediabetes or the heterogeneity of prediabetes.
Diabetes is the leading cause of kidney failure and new cases of blindness among adults in the
US. It is also associated with increased risks of cardiovascular disease, nonalcoholic fatty liver
disease, and nonalcoholic steatohepatitis and was estimated to be the seventh leading cause
of death in the US in 2017. Screening asymptomatic adults for prediabetes and type 2
diabetes may allow earlier detection, diagnosis, and treatment, with the ultimate goal of
improving health outcomes.
OBJECTIVE To update its 2015 recommendation, the USPSTF commissioned a systematic
review to evaluate screening for prediabetes and type 2 diabetes in asymptomatic,
nonpregnant adults and preventive interventions for those with prediabetes.
POPULATION Nonpregnant adults aged 35 to 70 years seen in primary care settings who have
overweight or obesity (defined as a body mass index 25 and 30, respectively) and no
symptoms of diabetes.
EVIDENCE ASSESSMENT The USPSTF concludes with moderate certainty that screening for
prediabetes and type 2 diabetes and offering or referring patients with prediabetes to
effective preventive interventions has a moderate net benefit.
CONCLUSIONS AND RECOMMENDATION The USPSTF recommends screening for prediabetes
and type 2 diabetes in adults aged 35 to 70 years who have overweight or obesity. Clinicians
should offer or refer patients with prediabetes to effective preventive interventions.
(B recommendation)

Standards of Medical Care in Diabetes—2019 Abridged for Primary Care Providers

Author/s: 
American Diabetes Association

The American Diabetes Association’s (ADA’s) Standards of Medical Care in Diabetes is updated and published annually in a supplement to the January issue of Diabetes Care. The ADA’s Professional Practice Committee, which includes physicians, diabetes educators, registered dietitians (RDs), and public health experts, develops the Standards. The Standards include the most current evidence-based recommendations for diagnosing and treating adults and children with all forms of diabetes. ADA’s grading system uses A, B, C, or E to show the evidence level that supports each recommendation.

  • A—Clear evidence from well-conducted, generalizable randomized controlled trials that are adequately powered

  • B—Supportive evidence from well-conducted cohort studies

  • C—Supportive evidence from poorly controlled or uncontrolled studies

  • E—Expert consensus or clinical experience

This is an abridged version of the 2019 Standards containing the evidence-based recommendations most pertinent to primary care. The tables and figures have been renumbered from the original document to match this version. The complete 2019 Standards of Care document, including all supporting references, is available at professional.diabetes.org/standards.

Keywords 
standard of care guidelines diabetes diabetes, type 2 A1C
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