Regional differences of undiagnosed type 2 diabetes and prediabetes prevalence are not explained by known risk factors.
BACKGROUND
We have previously found regional differences in the prevalence of known type 2 diabetes between northeastern and southern Germany. We aim to also provide prevalence estimates for prediabetes (isolated impaired fasting glucose (i-IFG), isolated glucose intolerance (i-IGT), combined IFG and IGT) and unknown type 2 diabetes for both regions.


METHODS
Prevalence (95%CI) of prediabetes (i-IFG: fasting glucose 5.6-6.9 mmol/l; i-IGT: 2 h postchallenge glucose 7.8-11.0 mmol/l, oral glucose tolerance test (OGTT), ≥ 8 h overnight fasting) and unknown diabetes were analyzed in two regional population-based surveys (age group 35-79 years): SHIP-TREND (Study of Health in Pomerania (northeast), 2008-2012) and KORA F4 (Cooperative Health Research in the region of Augsburg (south), 2006-2008). Both studies used similar methods, questionnaires, and identical protocols for OGTT. Overall, 1,980 participants from SHIP-TREND and 2,617 participants from KORA F4 were included.


RESULTS
Age-sex-standardized prevalence estimates (95%CI) of prediabetes and unknown diabetes were considerably higher in the northeast (SHIP-TREND: 43.1%; 40.9-45.3% and 7.1%; 5.9-8.2%) than in the south of Germany (KORA F4: 30.1%; 28.4-31.7% and 3.9%; 3.2-4.6%), respectively. In particular, i-IFG (26.4%; 24.5-28.3% vs. 17.2%; 15.7-18.6%) and IFG+IGT (11.2%; 9.8-12.6% vs. 6.6%; 5.7-7.5%) were more frequent in SHIP-TREND than in KORA. In comparison to normal glucose tolerance, the odds of having unknown diabetes (OR, 95%CI: 2.59; 1.84-3.65) or prediabetes (1.98; 1.70-2.31) was higher in the northeast than in the south after adjustment for known risk factors (obesity, lifestyle).


CONCLUSIONS
The regional differences of prediabetes and unknown diabetes are in line with the geographical pattern of known diabetes in Germany. The higher prevalences in the northeast were not explained by traditional risk factors.
Institute of Biometrics and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University, Düsseldorf, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Teresa
T
Tamayo
Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Sabine
S
Schipf
Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology II, Neuherberg, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Christine
C
Meisinger
Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Health Economics and Health Care Management, Neuherberg, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Michaela
M
Schunk
Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Health Economics and Health Care Management, Neuherberg, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Werner
W
Maier
Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University, Düsseldorf, Germany; German Center for Diabetes Research (DZD e.V.), Sites Düsseldorf and Munich, Germany.
Christian
C
Herder
Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University, Düsseldorf, Germany; Department of Endocrinology and Diabetology, University Hospital Düsseldorf, Düsseldorf, Germany; German Center for Diabetes Research (DZD e.V.), Sites Düsseldorf and Munich, Germany.
Michael
M
Roden
Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Matthias
M
Nauck
Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Epidemiology II, Neuherberg, Germany; German Center for Diabetes Research (DZD e.V.), Sites Düsseldorf and Munich, Germany; German Center of Cardiovascular Research (DZHK e.V.), Sites Munich and Greifswald, Germany.
Annette
A
Peters
Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany; German Center of Cardiovascular Research (DZHK e.V.), Sites Munich and Greifswald, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Henry
H
Völzke
Institute of Biometrics and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University, Düsseldorf, Germany; Competence Network Diabetes mellitus (Federal Ministry of Education and Research, Germany), Sites Düsseldorf, Munich and Greifswald, Germany.
Wolfgang
W
Rathmann
D000328:Adult; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000453:epidemiology*; D005215:Fasting; D005260:Female; D005843:Geography; D005858:Germany / Q000453:epidemiology; D018149:Glucose Intolerance / Q000175:diagnosis / Q000453:epidemiology*; D005951:Glucose Tolerance Test; D006306:Health Surveys; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D011236:Prediabetic State / Q000175:diagnosis / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors; D055815:Young Adult