Is low birth weight a risk factor for the development of diabetic nephropathy in patients with type 1 diabetes? A population-based case-control study

OBJECTIVES: To investigate if low birth weight as a consequence of intrauterine malnutrition is a risk factor for the later development of diabetic nephropathy.

DESIGN AND SUBJECTS: In a case-control set-up a group of type 1 diabetic subjects with diabetic nephropathy (n = 51) and a matched control group with normal kidney function (n = 51) were compared. Diabetic nephropathy and normal kidney function were defined as urinary albumin excretion rate above 200 microg min-1 and below 20 microg min-1, respectively. The birth weights were all obtained from the midwives' original records.

SETTING: The patients were identified from a population-based study of chronic diabetic complications in the Funen County, Denmark.

MAIN OUTCOMES: Birth weights according to the presence of diabetic nephropathy.

RESULTS: The median (10-90 percentile) birth weights were 3,600 g (2,960-4,274) in the group with diabetic nephropathy and 3,600 g (2,880-4,220) in the group without nephropathy, P = 0.52. In the lower quartile of birth weights the median (10-90 percentile) birth weights were 3,000 g (2,780-3,200) in the group with nephropathy versus 2,850 g (2,250-3,175) in the group without nephropathy, P = 0.07. In the upper quartile the median (10-90 percentile) birth weights were 4,225 g (4,000-4,741) in the nephropathy group and 4,000 g in the group without nephropathy, P = 0.13. We found no significant correlation between birth weights and log urinary albumin excretion rate (r = 0.148, P = 0.14) and no difference in the number of patients with nephropathy in the lower versus upper quartiles of birth weights.

CONCLUSION: We found no evidence of low birth weight as a risk factor for the development of diabetic nephropathy.