U.S. Diabetes Rate Climbs Above 11%; Could Hit 15% by 2015

by Dan Witters

Obesity and exercise are crucial factors; some states bucking national trend

WASHINGTON, D.C. -- The Gallup-Healthways Well-Being Index finds the reported incidence of diabetes on the rise in the United States, climbing to 11.3% of American adults -- or about 26 million Americans -- in the third quarter of 2009, up from 10.4% in the first quarter of 2008. If current trends continue, 15% of American adults -- or more than 37 million Americans -- will be living with diabetes by the end of 2015.

Have You Ever Been Told by a Physician or Nurse That You Have Diabetes?

"Americans who are obese are nearly three times as likely as those who are not obese to report having been diagnosed with diabetes."

The U.S. obesity rate, which has a well-established relationship with diabetes incidence, is up about one percentage point in quarter-over-quarter comparisons with 2008 results. (Obesity is assessed on the basis of respondents' self-reports of their height and weight, which are then used to calculate standard Body Mass Index scores. Individual BMI values of 30 or above are classified as "obese.")

Obesity Trend, Quarter 1, 2008, Through Quarter 3, 2009

The upward trends in obesity rates almost certainly play a substantive role in the increase in diabetes rates over the same time period. Americans who are obese are nearly three times as likely as those who are not obese to report having been diagnosed with diabetes. More than one-fifth (21.2%) of obese adults are diabetics, compared to 7.4% of non-obese adults.

Likelihood of Having Been Diagnosed With Diabetes: Obese vs. Non-Obese

The Relationship Between Exercise and Diabetes

One of the best ways to reduce obesity is through exercise, and a correlation between exercise and diabetes incidence is indeed found in the Gallup-Healthways data. In a review of January through September 2009 results, a sharply higher incidence of reported diabetes is found among those who did not exercise at least 30 minutes on any day in the previous week.

Exercise Habits and Diabetes Incidence

The positive relationship between exercise and reduced diabetes rates prevails even after controlling for weight class, as both obese and non-obese adults who did not exercise in the last week are more likely to say they have been diagnosed with diabetes than are their intra-weight-class counterparts who exercised. Even among obese adults, therefore, the likelihood of having been diagnosed with diabetes is lower among those who report engaging in at least some exercise each week, consisting minimally of one to three 30-minute workouts.

General long-term trends in exercise are also consistent with the relationships noted above. While exercise is seasonal and is expected to climb in the warmer months, year-over-year comparisons reveal a 2009 decline of 2.7 points in the percentage of American adults (nationally, about 6 million fewer people) who say they are exercising at least 30 minutes three or more times per week, compared with 2008.

Percentage of American Adults Who Exercised 30 Minutes or More at Least Three Days in Previous Week

Reversing the Trend

State-level analysis of diabetes and obesity reveals that it is possible to reverse the current national trends. The 10 states with the highest increases in obesity from 2008 to 2009 (Wyoming, Alaska, Minnesota, Maine, Idaho, Tennessee, Iowa, New Hampshire, North Dakota, and Texas) have on average also seen a concomitant increase of 0.5 percentage points in diabetes incidence. However, the 10 states whose rates have remained unchanged or have decreased since last year (Delaware, Montana, Kansas, Nebraska, South Dakota, Louisiana, Virginia, Missouri, Nevada, and Florida) have seen an average reduction in reported diabetes incidence by 0.3 percentage points, thus providing tangible state-level examples for future study to enhance understanding of managing diabetes nationally.

State-Level Changes in Obesity and Subsequent Average Change in Diabetes Rate

The Gallup-Healthways Well-Being Index data on obesity and diabetes are subcomponents of the Physical Health Sub-Index, on which North Dakota and West Virginia -- the best and worst states, respectively, in terms of diabetes -- also rank best and worst, respectively, for overall physical health. The Physical Health Sub-Index is one of six domains used to calculate the overall wellbeing score.

Learn more about the Gallup-Healthways Well-Being Index.

Survey Methods

Results are based on telephone interviews with 623,538 national adults, aged 18 and older, conducted Jan. 2, 2008, through Sept. 30, 2009, as part of the Gallup-Healthways Well-Being Index.

Approximately n=88,000-90,000 surveys are completed each quarter. For quarterly results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±0.3 percentage points.

In January through September 2009, n=274,278 completed surveys were conducted, including n=72,471 respondents that were computed to be obese.

The diabetes incidence survey question that is asked does not differentiate between Type 1 (juvenile) and Type 2 (adult onset) diabetes, the latter of which is linked to obesity. Type 2 diabetes is the far more common of the two types.

Interviews are conducted with respondents on land-line telephones (for respondents with a land-line telephone) and cellular phones (for respondents who are cell-phone only and cell-phone mostly).

In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.

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