Impact of Physical Activity on Cardiovascular Risk Factors in Children With Type 1 Diabetes

A multicenter study of 23,251 patients

  1. Antje Herbst, MD1,
  2. Olga Kordonouri, MD2,
  3. Karl O. Schwab, MD3,
  4. Frank Schmidt, MD4,
  5. Reinhard W. Holl, PHD5 and
  6. on behalf of the DPV Initiative of the German Working Group for Pediatric Diabetology Germany
  1. 1Pediatrics, Hospital of Leverkusen, Leverkusen, Germany
  2. 2Diabetes Center for Children and Adolescents, Children's Hospital auf der Bult, Hannover, Germany
  3. 3Pediatrics, University of Freiburg, Freiburg, Germany
  4. 4Pediatrics, University of Halle, Halle, Germany
  5. 5Epidemiology, University of Ulm, Ulm. Germany
  1. Address correspondence and reprint requests to Dr. Antje Herbst, MD, Pediatric Diabetology, Hospital of Leverkusen, Am Gesundheitspark 11, 51375 Leverkusen, Germany. E-mail: herbst{at}klinikum-lev.de

Type 1 diabetes is associated with a high risk for early atherosclerotic complications. Patients with type 1 diabetes have a fourfold (in men) to eightfold (in women) excess risk of coronary heart disease compared with that for the general population (1). It has been shown that type 1 diabetic patients aged 20–39 years have a fivefold higher risk of dying from cardio- and cerebrovascular events compared with that for healthy individuals (2). Development of atherosclerotic lesions in healthy subjects begins upon childhood. In children with type 1 diabetes who had died an unnatural death, an asymptomatic increase in the intima-media thickness of the common carotid artery was found (3). Known risk factors for vascular complications are long-standing diabetes, age, poor glycemic control, smoking, hypertension, obesity, and dyslipidemia (46). In a recent study, 69% of the pediatric patients with type 1 diabetes were found to have one or more cardiovascular risk factors (7). Thus, there is an urgent need for prevention strategies to reduce these risk factors in childhood and adolescence.

We recently showed that frequency of regular physical activity (RPA) represents an important factor influencing glycohemoglobin and, in girls, BMI (8). The present study focuses on the impact of RPA on further cardiovascular risk factors such as plasma lipids and blood pressure in children with type 1 diabetes.

RESEARCH DESIGN AND METHODS—

Data were provided by the Pediatric Quality Initiative (9) and included anonymous longitudinal data of 23,251 patients (3–18 years) with type 1 diabetes from 209 centers in Germany and Austria. The data are continuously generated by the participating centers using the diabetes data acquisition system for prospective surveillance [DPV] software (Diabetes Software for Prospective Documentation) and after anonymization are transmitted to the Pediatric Quality Initiative for central analysis. Plausibility of the data is reviewed twice a year, and inconsistent data are reconfirmed with the centers.

In this cross-sectional study (DPV Science database, October 2006), the following cardiovascular risk factors were evaluated: plasma lipids (cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides), blood pressure, A1C, and BMI. Laboratory methods are standardized nationwide and follow criteria for quality management defined by the German Medical Association (10). Dyslipidemia was defined as cholesterol >200 mg/dl (5.2 mmol/l), HDL cholesterol <35 mg/dl (0.91 mmol/l), LDL cholesterol >160 mg/dl (4.1 mmol/l), or triglycerides >150 mg/dl (1.7 mmol/l) (11). Normative blood pressure data developed by the Task Force on Blood Pressure Control in children served as reference values (12). For comparison, the A1C values were standardized and transformed to the Diabetes Control and Complications Trial normal range (13).

Baseline characteristics of the patients are shown in Table 1. Patients were grouped by the frequency of their self-reported RPA as follows: RPA0 = none (n = 10,392), RPA1 = 1–2 times/week (n = 8,607), and RPA2 = ≥3 times/week (n = 4,252). At every visit to the diabetologist, the DPV software requires information about the frequency of the patient's RPA, which represents exercise performed at least once a week for at least 30 min. Intensity of the sports activity is not included in the protocol. School sports are also not included. The study protocol was approved by the Human Subjects Research Committee of the University of Ulm.

The data were evaluated statistically using the Kruskal-Wallis test for comparison among groups followed by the Holm adjustment (Bonferroni stepdown) for multiple comparisons (SAS for Windows, version 9.1; SAS Institute, Cary, NC). Multiple linear regression analysis was performed to extract possible explanatory variables affecting the levels of cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides, A1C, and blood pressure. P < 0.05 was considered statistically significant.

RESULTS—

Mean A1C was 7.9%. The frequency of RPA ranged between 0 and 9 times/week (average 1.29 times/week). Of the patients, 44.7% were not physically active, 37.0% performed RPA 1–2 times/week, and 18.3% performed RPA ≥3 times/week. The age of the patients was higher with increasing frequency of RPA (P < 0.00001). Frequency of RPA was higher in boys than in girls (P < 0.01).

Dyslipidemia was seen in 37.9% of the patients. Elevations of cholesterol or of triglycerides were the most frequent types of dyslipidemia (24.3 and 25.8%, respectively), followed by elevated LDL cholesterol (14.2%) and decreased HDL cholesterol (3.1%). With increasing frequency of RPA, the percentage of patients with dyslipidemia decreased from 41.2% in the RPA0 group to 36.0% in the RPA1 group and 34.4% in the RPA2 group (P < 0.00001). Girls had higher values of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides than boys (P < 0.001). In girls, with increasing frequency of RPA, we found lower levels for total cholesterol (P < 0.015), LDL cholesterol (P < 0.005), and triglycerides (P < 0.00001) and higher levels for HDL cholesterol (P < 0.00001), whereas in boys there were differences only for HDL cholesterol (P < 0.00001) and triglycerides (P < 0.0005). Increasing frequency of RPA was associated with lower total cholesterol, LDL cholesterol, and triglycerides in the 15- to 18-year age-group, whereas in the 9- to 14-year age-group, it was associated with lower LDL cholesterol and higher HDL cholesterol. In the 3- to 8-year age-group, only the effect on HDL cholesterol reached significance. Multiple analyses revealed that HDL cholesterol and triglycerides were influenced by the frequency of RPA whereas cholesterol and LDL cholesterol were not.

Of the patients, 8.1% showed elevated systolic and 3.1% showed elevated diastolic blood pressures. There was no difference in systolic or diastolic blood pressures among the RPA groups. However, multiple analyses revealed that the percentage of patients with elevated diastolic blood pressure was lower in the RPA1 and RPA2 groups than in the RPA0 group (P < 0.005).

Multivariate analysis with A1C as the dependent variable revealed that frequency of RPA was one of the most important factors influencing A1C. A1C was lower in patients with a higher frequency of RPA (P < 0.00001), and this effect was found in both sexes and in all age-groups. Other factors associated with lower A1C were young age (P < 0.0001), male sex (P < 0.0001), and diabetes duration (P < 0.0001). Higher levels of A1C were associated with higher levels of cholesterol, LDL cholesterol, and triglycerides (P < 0.0001 each) and a lower level of HDL cholesterol (P < 0.01).

CONCLUSIONS—

Increasing physical activity in children with type 1 diabetes is associated with a beneficial cardiovascular risk profile, such as lower lipoprotein levels and diastolic blood pressure, and with better glycemic control. There are positive interactions between these parameters. Therefore, physical activity should represent an important issue in education of children and adolescents with type 1 diabetes and be performed regularly by these patients. The percentage of children with type 1 diabetes not performing any regular physical activity should be reduced.

Table 1—

Baseline characteristics of the 23,251 patients investigated

Acknowledgments

The DPV Science Initiative was supported by the German Federal Ministry of Health, Novo Nordisk Germany, the Dr. Bürger-Büsing Foundation, the German Diabetes Foundation, the German Research Foundation, the German Medical Association, and the National Action Forum against diabetes mellitus.

The authors thank the pediatric diabetes centers from the following cities that joined the DPV Science Initiative and collaborated in this investigation: Aachen, Ahlen, Altötting, Aue, Augsburg, Aurich, Bad Aibling, Bad Driburg, Bad Hersfeld, Bad Kösen, Bad Lauterberg, Bad Oeynhausen, Bad Waldsee, Berlin, Bielefeld, Bocholt, Bochum, Bonn, Bottrop, Bremen, Bremerhaven, Bruckmühl, Celle, Chemnitz, Coesfeld, Darmstadt, Datteln, Deggendorf, Delmenhorst, Detmold, Dornbirn, Dortmund, Dresden, Düren-Birkesdorf, Düsseldorf, Duisburg, Erfurt, Erlangen, Essen, Esslingen, Eutin, Frankfurt, Freiburg, Friedberg, Friedrichshafen, Fulda, Fürth, Gaissach, Garmisch-Partenkirchen, Gelnhausen, Gelsenkirchen, Gießen, Göppingen, Görlitz, Göttingen, Graz, Hachenburg, Hagen, Halle, Hamburg, Hamm, Hanau, Hannover, Heidelberg, Heidenheim, Heilbronn, Herdecke, Herford, Heringsdorf, Hermeskeil, Herten, Hildesheim, Hinrichsegen-Bruckmühl, Homburg, Idar-Oberstein, Innsbruck, Itzehoe, Jena, Kaiserslautern, Karlsburg, Karlsruhe, Kassel, Kaufbeuren, Kempen, Kiel, Kirchheim-Nürtingen, Koblenz, Köln, Konstanz, Krefeld, Landshut, Leipzig, Leverkusen, Lindenfels, Lingen, Lippstadt, Ludwigsburg, Ludwigshafen, Lübeck, Lüdenscheid, Magdeburg, Mainz, Mannheim, Marburg, Mechernich, Memmingen, Minden, Moers, Mönchengladbach, München, Münster, Mutterstadt, Neuburg, Neunkirchen, Neuss, Neuwied, Nürnberg, Oberhausen, Offenbach, Offenburg, Oldenburg, Osnabrück, Paderborn, Papenburg, Passau, Pforzheim, Rastatt, Ravensburg, Recklinghausen, Regensburg, Remscheid, Rendsburg, Rheine, Rosenheim, Rostock, Rotenburg/Wümme, Saaldorf-Surheim, Saalfeld, Saarbrücken, Saarlouis, Scheidegg, Schw. Gemünd, Schweinfurt, Schwerin, Siegen, Singen, Sinsheim, Stade, Stolberg, Stuttgart, Suhl, Sylt, Traunstein, Trier, Tübingen, Ulm, Vechta, Viersen, Waiblingen, Waldshut, Weiden, Weingarten, Wetzlar, Wien, Wiesbaden, Wilhelmshafen, Wittlich, Wolgast, Worms, and Wuppertal.

Footnotes

  • Published ahead of print at http://care.diabetesjournals.org on 27 April 2007. DOI: 10.2337/dc06-2636.

    A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

    The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C Section 1734 solely to indicate this fact.

    • Accepted April 20, 2007.
    • Received December 31, 2006.

References

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  1. Diabetes Care vol. 30 no. 8 2098-2100
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