Type 2 diabetes mellitus in nursing home patients: effects on bone turnover, bone mass, and fracture risk.
BACKGROUND
Fractures are a major health burden in elderly institutionalized persons. Type 2 diabetes mellitus (DM) has a high prevalence in nursing home patients and has been associated with positive effects on bone mass in younger, community-dwelling elderly.


OBJECTIVE
The objective of this study was to investigate whether type 2 DM affects bone mass, bone turnover, or prospective fracture rates in frail, elderly women living in nursing homes.


METHODS
This study was a prospective cohort of 583 patients with type 2 DM and 1081 control (CTR) individuals above age 70 recruited from 95 nursing homes in Austria. Patients were enrolled and followed up by mobile study teams.


METHODS
We performed quantitative bone ultrasound measurements at the calcaneus, radius, and proximal third phalanx, measurements of quadriceps strength, and biochemical parameters of mineral metabolism and bone turnover. Patients were prospectively followed for hip and other nonvertebral fractures over 2 yr.


RESULTS
Patients with type 2 DM had significantly higher age-, weight-, and mobility score-adjusted calcaneal stiffness (P < 0.0001), radial speed of sound (P < 0.005), and phalangeal speed of sound (P < 0.05) measurements when compared with CTRs. Mean serum PTH (-20.7%) and osteocalcin levels (-22.3%) were significantly lower (both P < 0.0001) in patients with treated type 2 DM despite comparable low serum 25-hydroxyvitamin D levels and slightly higher adjusted total serum calcium levels compared with CTRs. Important independent determinants of bone turnover in both patient groups were PTH, creatinine clearance, alanine aminotransferase, as well as glycosylated hemoglobin levels, together accounting for 30-40% of its variance. A total of 110 hip fractures occurred during the observation period, corresponding to a hip fracture rate of 3.1% (in CTRs) and 3.4% (in type 2 DM) per 100 patient years; this was not significantly different for CTRs and diabetics.


CONCLUSIONS
Decreased PTH levels and higher levels of glycemia independently contribute to lower bone turnover in elderly nursing home patients with type 2 DM. Despite higher bone mass and lower bone turnover, hip fracture risk is comparable with women without DM.
Dobnig
Harald
H
Department of Internal Medicine, Division of Endocrinology and Nuclear Medicine, Medical University of Graz, Auenbruggerplatz 15, A-8036 Graz, Austria. harald.dobnig@meduni-graz.at
Piswanger-Sölkner
Jutta Claudia
JC
Roth
Martin
M
Obermayer-Pietsch
Barbara
B
Tiran
Andreas
A
Strele
Andrea
A
Maier
Elisabeth
E
Maritschnegg
Peter
P
Sieberer
Christian
C
Fahrleitner-Pammer
Astrid
A
D000368:Aged; D000369:Aged, 80 and over; D001317:Austria / Q000453:epidemiology; D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000378:metabolism*; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology / Q000378:metabolism*; D005260:Female; D050723:Fractures, Bone / Q000097:blood / Q000453:epidemiology* / Q000378:metabolism; D006442:Glycated Hemoglobin / Q000032:analysis; D006620:Hip Fractures / Q000097:blood / Q000453:epidemiology / Q000378:metabolism; D006707:Homes for the Aged; D006801:Humans; D009735:Nursing Homes; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood; D011446:Prospective Studies; D052097:Quadriceps Muscle / Q000502:physiology; D014463:Ultrasonography; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
D006442:Glycated Hemoglobin; D015675:Osteocalcin; D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D