Relative risk of mortality associated with diabetes as a function of birth weight.

OBJECTIVE: Birth weight is a risk factor for both diabetes and mortality. Diabetes is a risk factor for mortality. Whether the excess mortality observed for diabetes varies with birth weight is unclear. RESEARCH DESIGN AND METHODS: Among all 2,508 Rochester, Minnesota, residents who first met research criteria for adult-onset diabetes in 1960-1995, 171 were born locally in-hospital after 1922 (i.e., birth weights available) as singleton, term infants. Each case subject and two age- and sex-matched nondiabetic control subjects (born locally, residing locally when the case subject met the criteria for diabetes) were followed through 31 December 2000 for vital status. RESULTS: Of the diabetic case subjects, 16% (27 of 171) died vs. 7% (25 of 342) of control subjects (P = 0.004). The difference was less for normal-birth-weight (NBW) (2,948-<3,856 g) individuals (12% [12 of 102] vs. 8% [20 of 246], P = 0.31) than for abnormal-birth-weight individuals (low birth weight [LBW] 20% [8 of 39] vs. 2% [1 of 46], P = 0.01; high birth weight [HBW] 23% [7 of 30] vs. 8% [4 of 50], P = 0.16), as confirmed with age- and sex-adjusted Cox proportional hazards (diabetes-associated hazard ratio 1.4 [95% CI 0.69-2.90] for NBW vs. 4.8 [1.7-13.3] for abnormal birth weight, test for interaction P = 0.056). The observed diabetes deaths were greater than expected, based on mortality for the general population (27 vs. 13.3, P < 0.001), with 70% of excess deaths occurring among LBW (8 vs. 2.2, P < 0.001) and HBW (7 vs. 3.1, P = 0.03) individuals. CONCLUSIONS: The excess mortality observed for diabetes appears disproportionately concentrated among abnormal-birth-weight individuals, thus identifying a subset of at-risk diabetic individuals and reinforcing the importance of NBW deliveries.

Fracture risk in primary hyperparathyroidism.

A key component in the decision to perform surgery on patients with primary hyperparathyroidism (HPT) is their skeletal status. Consequently, fracture risk in these patients has been investigated in a number of observational studies. Our group reported on a population-based cohort of residents from Rochester, MN, with primary HPT recognized during a 28-year period (1965-1992). The majority of these patients were asymptomatic, and most (77%) were managed conservatively. By contrast, a recent Danish study reported on a cohort of 674 patients, all of whom had surgery for primary HPT. Nonetheless, the risk of fracture was increased remarkably similarly in the two populations: vertebrae, approximately 3-fold; forearm, approximately 2-fold; hip, approximately 1.5-fold; and all fractures, approximately 1.5-fold. In both studies, parathyroid surgery seemed to have a protective effect. These (and previous studies) indicate that overall fracture risk is increased in primary HPT patients. An increase in forearm fracture risk is a relatively uniform finding and is consistent with known effects of parathyroid hormone (PTH) on cortical bone. However, the increase in vertebral fracture risk seen in most (but not all) studies does not fit with the observation that cancellous bone mass/structure is preserved in primary HPT patients. Based on these findings, future directions for research include (1) rigorously testing, in prospective studies, whether vertebral fracture risk is, in fact, increased in this disorder, and if so, determining the possible biomechanical mechanism(s) for this increase; and (2) testing whether the trend to increased hip fracture risk seen in some studies is real and whether it is more closely linked to cervical or intertrochanteric fractures.