In This Issue of Diabetes Care

Although it has been some time since initial findings were published that described an inverse association between coffee consumption and risk of type 2 diabetes, a new meta-analysis in this issue of Diabetes Care (p. 569) provides updated information on this relationship and adds a new dimension to the discussion by distinguishing caffeinated from decaffeinated coffee. The report by Ding et al. is based on a literature search that included 28 prospective studies published between 1966 and 2013. These reports, which included ∼1.1 million individuals and >45,000 diabetes cases, drew on diverse populations from the U.S., Europe, and Asia. Among other eligibility criteria, the studies had to categorize coffee consumption in a manner that permitted examination of both caffeinated and decaffeinated coffee. The follow-up for these studies ranged from 10 months to 20 years, with a median of 11 years. Consistent with previous observations, the new report indicated a strong relationship between total coffee consumption and decreased diabetes risk. Compared with those in people who did not consume any coffee, the relative risks for type 2 diabetes among people who drank 1, 2, 3, 4, 5, or 6 cups of coffee each day were 0.92, 0.85, 0.79, 0.75, 0.71, and 0.67, respectively, indicative of a dose-response relationship. Additional analyses indicated that both caffeinated coffee and decaffeinated coffee were associated with decreased risk. Relative to that in people with the lowest caffeinated coffee consumption level, the risk of diabetes was 0.92, 0.82, and 0.74 for the highest, second highest, and third highest categories, and findings were similar for decaffeinated coffee. Although the authors point out that methodological considerations such as misclassification and loss to follow-up could influence these results, they point out that these issues are likely to be nondifferential, thus limiting their impact on the results. Given that the magnitude of the protective effect of increasing coffee consumption was similar for caffeinated coffee and decaffeinated coffee, factors other than caffeine content may be responsible for coffee’s protective effect on diabetes. The mechanistic basis of this relationship is ripe for future investigation. — Helaine E. Resnick, PhD, MPH

Ding et al. Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. Diabetes Care 2014;37:569–586

It is widely recognized that diabetes prevention efforts among high-risk individuals can have a meaningful impact on progression to diabetes, as well as the costs that accompany diabetes and diabetes complications. Nonetheless, a new report in this issue of Diabetes Care (p. 565) suggests that even when prediabetes is identified in clinical records, limited steps are taken to retard its progression. Schmittdiel et al. examined electronic health records for more than 368,000 patients with prediabetes. Less than half of these patients had documentation suggesting that a clinical response occurred within 6 months, and only 13% were given a diagnosis of prediabetes. Further, only 18% of prediabetic patients had repeat glucose or A1C testing during this period, and <5% were referred to education or behavior modification programs. Notably, although 69% of all patients had fasting plasma glucose (FPG) 100–109 mg/dL, the investigators noted that patients whose FPG was at the high end of the prediabetes range (120–125 mg/dL) were more likely to have a clinical response, with 31% having repeat glucose testing and 25% receiving a prediabetes diagnosis. However, <1% of prediabetic patients with FPG 120–125 mg/dL started metformin. Despite the fact that people with prediabetes often progress to frank diabetes, the authors point out that current American Diabetes Association (ADA) guidelines do not call for initiation of metformin, nor do they recommend particular lifestyle modifications or programs for individuals with prediabetes. One of the reasons for this lack of direction may be the paucity of evidence regarding which strategies are most effective at improving outcomes for this population—a deficiency that could be addressed in the future by well-designed clinical trials. Successful trials have the potential to inform on approaches to reduce the progression to diabetes among increasing numbers of high-risk individuals who, if untreated, will contribute to the ongoing epidemic of diabetes. — Helaine E. Resnick, PhD, MPH

Schmittdiel et al. Novel use and utility of integrated electronic health records to assess rates of prediabetes recognition and treatment: brief report from an integrated electronic health records pilot study. Diabetes Care 2014;37:565–568

A new report in this issue of Diabetes Care (p. 529) underscores the public health and policy implications of the recommendation that adults engage in moderate-intensity physical activity on a regular basis. McAuley et al. studied more than 17,000 people who were part of the Aerobics Center Longitudinal Study (ACLS), a cohort of mostly middle class men and women that began in the 1970s. The new report identified participants who had prediabetes and who also completed a cardiorespiratory fitness (CRF) test in addition to measures of adiposity including BMI, waist circumference, and percent body fat. In this prediabetic cohort, there were 832 deaths, including 246 cardiovascular disease (CVD) deaths during an average of 13.9 years of follow-up. Results clearly showed the protective effects of fitness on all-cause mortality: Relative to people in the lowest tertile of CRF, those in the second and third tertiles had reductions in mortality risk of 29% and 37%, respectively. When these results were adjusted for adiposity, they remained unchanged, suggesting that adiposity did not impact the association. Similar results were observed for CVD mortality. Although initial models indicated that the risk of mortality was 53% higher among obese participants relative to their nonobese counterparts and that participants in the highest tertile of waist circumference had a 28% higher mortality risk than those in the lowest tertile, these differences were eliminated when CRF was considered, underscoring the important role that CRF plays in the association between adiposity and mortality. The new report emphasized that among fit individuals, there were no differences in all-cause or CVD mortality across categories of BMI, body fat, or waist circumference, but adiposity-related mortality effects were evident among unfit individuals—observations suggesting that a greater emphasis on achieving fitness, rather than reducing fatness, may be effective in reducing mortality risk. — Helaine E. Resnick, PhD, MPH

McAuley et al. Fitness, fatness, and survival in adults with prediabetes. Diabetes Care 2014;37:529–536

A report by Pettitt et al. in this issue of Diabetes Care (p. 402) shows that in 2009, nearly 192,000 people aged <20 years had diabetes. The report, which summarized recent data from the SEARCH for Diabetes in Youth Study (SEARCH), indicates that the overall prevalence of diabetes in people aged <20 years was 2.22 cases per 1,000 individuals, or about 1 case of diabetes for every 433 people in this age-group. The study shows that although the overall prevalence of diabetes was 0.30 per 1,000 among children aged 0–4 years, it increased to 4.03 per 1,000 among those aged 15–19 years. Further, the new data also show that although diabetes occurred with similar frequency in boys and girls, it was considerably more common in white children than in minority children. This excess of diabetes was explained by the fact that type 1 diabetes accounted for the vast majority of all cases in SEARCH, and type 1 diabetes cases were considerably more common among white youth. However, the new data offer important insight into what may be in store for American youth in the future: SEARCH data indicate that although type 2 diabetes cases were far outnumbered by type 1 diabetes cases, these cases occurred with greater frequency in minority youth. Given the increases in childhood obesity that have been demonstrated in recent years and the disproportionate impact of obesity on minority youth, it is likely that the racial disparities in type 2 diabetes that have been documented among adults for decades will also become a hallmark of American youth. — Helaine E. Resnick, PhD, MPH

Pettitt et al. Prevalence of diabetes in U.S. youth in 2009: the SEARCH for Diabetes in Youth Study. Diabetes Care 2014;37:402–408