Insulin deficiency at diagnosis of diabetes causes a catabolic state that is predominantly lipolytic. Body composition normalises within 6 weeks of treatment, though girls remain thinner than boys both at diagnosis and 1 year thereafter, in contrast to published findings. Despite girls being prescribed a larger insulin dose, their HbA1c and cholesterol levels are higher at 1 year suggesting increased insulin resistance and cardiovascular risk.
The impacts of hyper and hypothyroidism on body composition, i.e. the relative quantity and quality of bone, adipose tissue and muscle, have traditionally been attributed uniquely to abnormal levels of free thyroid hormones. The presence of biologically active TSH receptors in bone, fat and muscle, raises the possibility that both thyroid hormones and TSH contribute to the changes in body composition associated with thyroid disease. This review evaluates the evidence for this in terms of the in vitro experimental approaches applied, data from in vivo sources (i.e. mouse models) and patient-based studies.
OBJECTIVE
Proteomic profiling can identify useful biomarkers. Monozygotic (MZ) twins discordant for a condition represent an ideal test population. We aimed to investigate and validate proteomic profiling in twins with type 1 diabetes and in other well-characterized cohorts.
RESEARCH DESIGN AND METHODS
A broad, multiplex analysis of 4,068 proteins in serum samples from MZ twins concordant (n = 43) and discordant (n = 27) for type 1 diabetes identified major differences that were subsequently validated by a trypsin(ogen) assay in MZ pairs concordant (n = 39) and discordant (n = 42) for type 1 diabetes, individuals at risk for (n = 195) and with (n = 990) type 1 diabetes, as well as individuals with noninsulin-requiring adult-onset diabetes diagnosed as either autoimmune (n = 96) or type 2 (n = 291).
RESULTS
Proteomic analysis identified major differences between exocrine enzyme levels in discordant MZ twin pairs despite a strong correlation between twins, whether concordant or discordant for type 1 diabetes (P < 0.01 for both). In validation experiments, trypsin(ogen) levels were lower in twins with diabetes than in the cotwin without diabetes (P < 0.0001) and healthy control participants (P < 0.0001). In recently diagnosed participants, trypsin(ogen) levels were lower than in control participants across a broad age range. In at-risk relatives, levels <15 ng/mL were associated with an increased risk of progression (uncorrected P = 0.009). Multiple linear regression in recently diagnosed participants showed that trypsin(ogen) levels were associated with insulin dose and diabetic ketoacidosis, while age and BMI were confounders.
CONCLUSIONS
Type 1 diabetes is associated with altered exocrine function, even before onset. Twin data suggest roles for genetic and nongenetically determined factors. Exocrine/endocrine interactions are important underinvestigated factors in type 1 diabetes.
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