Prevalence of diabetes-specific autoantibodies in patients at risk for adult onset diabetes mellitus

Diabetes autoantibodies do not predict progression to diabetes in adults: the Diabetes Prevention Program

AIMS

To determine if the presence of diabetes autoantibodies predicts the development of diabetes among participants in the Diabetes Prevention Program.

METHODS

A total of 3050 participants were randomized into three treatment groups: intensive lifestyle intervention, metformin and placebo. Glutamic acid decarboxylase (GAD) 65 autoantibodies and insulinoma-associated-2 autoantibodies were measured at baseline and participants were followed for 3.2 years for the development of diabetes.

RESULTS

The overall prevalence of GAD autoantibodies was 4.0%, and it varied across racial/ethnic groups from 2.4% among Asian-Pacific Islanders to 7.0% among non-Hispanic black people. There were no significant differences in BMI or metabolic variables (glucose, insulin, HbA(1c), estimated insulin resistance, corrected insulin response) stratified by baseline GAD antibody status. GAD autoantibody positivity did not predict diabetes overall (adjusted hazard ratio 0.98; 95% CI 0.56-1.73) or in any of the three treatment groups. Insulinoma-associated-2 autoantibodies were positive in only one participant (0.033%).

CONCLUSIONS

These data suggest that 'diabetes autoimmunity', as reflected by GAD antibodies and insulinoma-associated-2 autoantibodies, in middle-aged individuals at risk for diabetes is not a clinically relevant risk factor for progression to diabetes.

The peripheral GABAergic system as a target in endocrine disorders

In addition to its well-recognized function as a cerebral inhibitory transmitter, less well established is the role of GABA in peripheral nervous and endocrine systems. We summarize current evidence that GABA serves as a neurotransmitter or neuromodulator in the autonomic nervous system and as a hormone or trophic factor in non-neuronal peripheral tissue as well. GABA is widely distributed in endocrine tissues including the pituitary, pancreas, adrenal glands, uterus, ovaries, placenta and testis. Moreover, GABA is involved in the pathophysiology of endocrine disorders such as diabetes mellitus, diseases of adrenal glands and reproductive tracts. Current literature indicates that the peripheral GABA system in the autonomic nervous system, endocrine and immune systems is as yet nearly an unexplored target for diagnosis and drug treatment.

Insulin intervention to preserve beta cells in slowly progressive insulin-dependent (type 1) diabetes mellitus

Slowly progressive insulin-dependent (type 1) diabetes mellitus (SPIDDM) is characterized by (1) late age of onset, with initial features of NIDDM and subsequent progression to insulin-dependent stage; (2) high predictive value of autoantibodies against glutamic acid decarboxylase (GADAb) and islet cell antibodies (ICA) for progression of beta cell failure; (3) less predominant T cell response, which may attack and eventually destroy beta-cells in affected pancreas. These findings may suggest a rationale for intervention to prevent slowly progressive beta cell dysfunction in this type of diabetes. We identified three independent risk factors for progression of beta cell failure in SPIDDM: (1) sulfonylurea treatment; (2) ICA-positive periods; and (3) initial body weight. We hypothesized that removal of the risk factors for further progression of beta cell dysfunction will have beneficial effects on intervention strategy in treating SPIDDM. In our pilot study, we used a small dose of insulin instead of sulfonylurea in the early stage of treatment of patients with SPIDDM. Insulin-treated SPIDDM patients had a sustained C peptide response (CPR), while most of sulfonylurea-treated patients progressed to an insulin-dependent state. We organized a randomized multicenter clinical trial to study early treatment to prevent the progression of beta cell dysfunction in SPIDDM (the Tokyo Study). It was demonstrated that early intervention with insulin therapy is an effective treatment modality in the early stage of SPIDDM patients who had preserved beta cell function at entry (integrated value of serum C peptide values at 0, 30, 60, 90, and 120 minutes; Sigma CPR >or= 10 ng/mL) and high GADAb (>10 U/mL). Preventive insulin treatment was ineffective in the patients who had diminished insulin reserve at entry (Sigma CPR < 10 ng/mL). Insulin intervention to preserve beta cell dysfunction in SPIDDM is effective and safe in patients with preserved beta cell function and high GADAb titers at the initiation of insulin.

All-cause mortality in the Canterbury (New Zealand) insulin-treated Diabetic Registry population

OBJECTIVE

To establish all-cause death rates and life expectancies of and risk factors for mortality in insulin-treated diabetic individuals living in Canterbury, New Zealand.

RESEARCH DESIGN AND METHODS

Insulin-treated diabetic subjects (n = 1,008) on the Canterbury Diabetes Registry were tracked over 9 years, and their vital status was determined. Death rates were standardized using direct and indirect methods. Cox proportional hazard regression was used to model the effects of demographic and clinical covariates on survival time.

RESULTS

At study entry, age ranged from 2.9 to 92.7 years, with mean 48.7 +/- 20.4 years; age at diagnosis was 0.2-88.9 years, mean 34.5 +/- 20.0 years; and duration of diabetes was 0.1-58.5 years, mean 14.0 +/- 10.6 years. There were 303 deaths in 7,372 person-years of follow-up with a standardized mortality ratio (SMR) of 2.6 (95% CI 2.4-3.0). Relative mortality was greatest for those aged 30-39 years (SMR 9.2 [4.8-16.2]). The death rate for the diabetic cohort standardized against the Segi world standard population was 16.2 per 1,000. Attained age, sex, and clinical subtype were significant predictors of mortality The SMR for subjects with type 1 diabetes and age at onset <30 years was 3.7 (CI 2.7-5.0), 2.2 (1.8-2.6) for those with onset > or =30 years, and 3.1 (2.5-3.7) for subjects suspected of having latent autoimmune diabetes in adulthood or insulin-treated type 2 diabetes. Life expectancy was reduced for both sexes at all ages.

CONCLUSIONS

Mortality rates for insulin-treated diabetic individuals remain high, resulting in shortened life spans relative to the general population. Marked differences in mortality exist between clinical groups of subjects. Further research is needed to improve diabetes classification and to clarify differences in health outcomes.