Differential Associations of GAD Antibodies (GADA) and C-Peptide With Insulin Initiation, Glycemic Responses, and Severe Hypoglycemia in Patients Diagnosed With Type 2 Diabetes

OBJECTIVEWe examined the associations of GAD antibodies (GADA) and C-peptide (CP) with insulin initiation, glycemic responses, and severe hypoglycemia in type 2 diabetes (T2D). RESEARCH DESIGN AND METHODSIn 5,230 Chinese patients (47.6% men) with T2D (mean +/- SD age: 56.5 +/- 13.9 years; median diabetes duration: 6 [interquartile range 1, 12] years), enrolled consecutively in 1996-2012 and prospectively observed until 2019, we retrospectively measured fasting CP and GADA in stored serum and examined their associations with aforementioned outcomes. RESULTSAt baseline, 28.6% (n = 1,494) had low CP (<200 pmol/L) and 4.9% (n = 257) had positive GADA (GADA+). In the low-CP group, 8.0% had GADA+, and, in the GADA+ group, 46.3% had low CP. The GADA+ group had an adjusted hazard ratio (aHR) of 1.46 (95% CI 1.15-1.84, P = 0.002) for insulin initiation versus the GADA- group, while the low-CP group had an aHR of 0.88 (0.77-1.00, P = 0.051) versus the high-CP group. Following insulin initiation, the GADA+ plus low-CP group had the largest decrements in HbA(1c) (-1.9% at month 6; -1.5% at month 12 vs. -1% in the other three groups). The aHR of severe hypoglycemia was 1.29 (95% CI 1.10-1.52, P = 0.002) in the low-CP group and 1.38 (95% CI 1.04-1.83, P = 0.024) in the GADA+ group. CONCLUSIONSThere is considerable heterogeneity in autoimmunity and beta-cell dysfunction in T2D with GADA+ and high CP associated with early insulin initiation, while GADA+ and low CP, increased the risk of severe hypoglycemia. Extended phenotyping is warranted to increase the precision of classification and treatment in T2D.

Automated summary

This study examined the associations of GAD antibodies (GADA) and C-peptide (CP) with insulin initiation, glycemic responses, and severe hypoglycemia in Chinese patients with type 2 diabetes (T2D). The results showed that GADA+ and high CP were associated with early insulin initiation, while GADA+ and low CP increased the risk of severe hypoglycemia.