Diabetes – some recent findings

1. From Aerobic Exercise Capacity and Pulmonary Function in Athletes With and Without Type 1 Diabetes, by Komatsu et al. (link):

“In this study, we have shown that athletes with type 1 diabetes have a Vo2peakmax [aerobic exercise capacity] similar to that of athletes without diabetes but a lower anaerobic threshold than that of athletes without diabetes.

In a previous study (6), we demonstrated that nonathletic type 1 diabetic patients have a lower Vo2peak max than healthy subjects. In the present study, we confirm these data in nonathletic type 1 diabetic patients, but the defect (low Vo2peak max) was not found in athletes with type 1 diabetes. These data are in accordance with a study (11) that compared 128 patients with long-duration type 1 diabetes and 36 healthy individuals. […]

All of the individuals in this study went to heart rate max frequency during the test. However, the type 1 diabetes sedentary group had lower maximum heart rate than the control group, as expected. This was an interesting finding and one in accordance with our previous data (6) in which the diabetic group showed lower maximum frequency during exercise than normal control subjects. This defect could be corrected with regular exercise since the diabetic athlete was able to achieve the same maximum heart rate as a normal athlete.

In this study, we also found that FEV1 [volume that has been exhaled at the end of the first second of forced expiration] was decreased in type 1 diabetic athletes compared with other groups. […] Abnormalities in lung elasticity behavior can be manifestations of widespread elastin and collagen abnormalities in type 1 diabetic patients (14). These alterations have been demonstrated in diabetes and are, in some respects, similar to those that occur during normal aging.”

I found the ‘lower anaerobic threshold’ particularly interesting as this threshold can probably be considered a significant limiting factor when you run (/half-)marathons and similar. If the threshold is lower, the inevitable buildup of lactic acid will start sooner or at a lower absolute activity level, meaning you simply can’t run as fast.

2. A follow-up on the All-Cause Mortality Trends in a Large Population-Based Cohort With Long-Standing Childhood-Onset Type 1 Diabetes study from ‘The Allegheny County Type 1 Diabetes Registry’, a previous version of which I’m pretty sure I’ve linked to before, has now been done, adding 9 more years of follow-up to the analysis. Here’s the link. Conclusions:

“Although survival has clearly improved, those with diabetes diagnosed most recently (1975–1979) still had amortality rate 5.6 times higher than that seen in the general population, revealing a continuing need for improvements in treatment and care, particularly for women and African Americans with type 1 diabetes.” […]

“Of note, now with a range of 28–43 years of type 1 diabetes duration, the risk of dying is 7 times higher than that of the local general population, with significant improvements in SMR [Standardized Mortality Ratios, US] for those with diabetes diagnosed most recently in this cohort.” […] This is the largest population-based type 1 diabetes cohort with at least 25 years of follow-up in the U.S. A recent population-based 20-year follow-up study in New Zealand showed the highest SMRs in individuals with type 1 diabetes diagnosed at age <30 (3.3 for men and 4.3 for women) (14). A nationwide Norwegian cohort with childhood-onset (age <15 years) type 1 diabetes recently reported SMRs of 3.9 (male) and 4.0 (female) after 20 years of follow-up (6).”

So what does this look like? The short version is this:

Graph number 3 directly above graphs the survival probability for the groups diagnosed during 65-69, 70-74 and 75-79; as can be seen quite clearly mortality is lower for the people diagnosed later in time, reflecting the progress that has taken place in treatment options and management of the disease. Note that these are not ‘historical figures’ – I got diagnosed in 87, just 8 years after the last of these cutoffs.

The US is quite different from the other countries analyzed in a few respects, in particular when it comes to the outcomes of the females: “The respective male-to-female mortality RRs [rate ratios, US] for these studies are 1.23 in New Zealand, 2.26 in Norway, and 1.29 in the U.K compared with 0.80 for our study. The reason for this discrepancy is unclear, but it appears that female sex completely lost its general survival advantage in our diabetes population. […] Women in our cohort die at a rate similar to that of men, a result warranting further exploration, as younger women die much less frequently than younger men in the general U.S. population.”

What about race, I hear you ask? Well: “Despite race being a significant predictor of mortality within the Allegheny County cohort (hazard ratio 3.2), no differences in SMR were seen by race, the African American SMR tending to be lower than the Caucasian SMR during follow-up (Fig. 2C). This seemingly contradictory result can be explained by the extremely high mortality rates seen in young African-Americans in the general population, particularly resulting from violent deaths (20)”

3. Changes in the Incidence of Lower Extremity Amputations in Individuals With and Without Diabetes in England Between 2004 and 2008, by Vamos et al. (link). From the study:

“RESEARCH DESIGN AND METHODS We identified all patients aged >16 years who underwent any nontraumatic amputation in England between 2004 and 2008 using national hospital activity data from all National Health Service hospitals. Age- and sex-specific incidence rates were calculated using the total diabetes population in England every year. To test for time trend, we fitted Poisson regression models.

RESULTS The absolute number of diabetes-related amputations increased by 14.7%, and the incidence decreased by 9.1%, from 27.5 to 25.0 per 10,000 people with diabetes, during the study period (P > 0.2 for both). The incidence of minor and major amputations did not significantly change (15.7–14.9 and 11.8–10.2 per 10,000 people with diabetes; P = 0.66 and P = 0.29, respectively). Poisson regression analysis showed no statistically significant change in diabetes-related amputation incidence over time (0.98 decrease per year [95% CI 0.93–1.02]; P = 0.12). Nondiabetes-related amputation incidence decreased from 13.6 to 11.9 per 100,000 people without diabetes (0.97 decrease by year [0.93–1.00]; P = 0.059). The relative risk of an individual with diabetes undergoing a lower extremity amputation was 20.3 in 2004 and 21.2 in 2008, compared with that of individuals without diabetes. […]

In summary, in this study we found no evidence that the incidence of amputations has significantly decreased over the last 5 years among people with diabetes in England. In contrast to the results from regional studies in England, the population burden of amputations increased in people with diabetes at a time when both the number and incidence of amputations decreased in the aging general population. There is strong evidence to support the fact that much of this burden is preventable through existing interventions, and our findings highlight the need to further improve foot care for people with diabetes.”

September 21, 2011 - Posted by | Data, Diabetes, Epidemiology, Medicine

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