The term “latent onset autoimmune diabetes in the adult” (LADA) has been introduced to define adult patients with diabetes, who are initially, non-insulin requiring and appear to have type 2 diabetes mellitus. These persons have however been found to have immune markers of type 1 diabetes and often progress to insulin dependency. Aims and Objectives of Study The aim of this study was to investigate the frequency and characteristic features of LADA based on the presence of Glutamic acid decarboxylase (GAD) antibodies in patients who had been clinically diagnosed as type 2 diabetes mellitus. Characteristics of these Glutamic acid decarboxylase antibody (GADA) positive and GADA negative patients were also compared. Methodology One hundred and sixty patients who had been diagnosed clinically to have type 2 diabetes mellitus (CT2DM) and one hundred control subjects were included in the study. Anthropometric measurements (weight, height, waist circumference, and hip circumference) were taken and blood samples were obtained for analysis of fasting blood glucose, glycated haemoglobin (HbA1c) and GAD antibodies from the patients with CT2DM. All the persons in the control group had fasting or random blood glucose checks with a glucometer to exclude previously undiagnosed diabetes mellitus. The results obtained were analyzed using SPSS package version 16. Results Out of the 160 patients with CT2DM, 65 (40.6%) were males while 95(59.4%) were females. The 100 control subjects included 37 (37%) males, and 63 (63%) females. The mean age (SD) of the patients with CT2DM was 60.49 (10.37) years, the mean BMI (SD) was 26.47 (4.80) kg/m2 while the mean waist circumference (SD) was 92.16 (11.50)cm. Nineteen persons (11.9%) amongst patients with CT2DM were positive for GADA while 5 (5%) of the control subject were positive for GADA. Subjects with CT2DM who were GADA positive had a lower mean BMI (25.64 kg/m2 vs. 26.59 kg/m2 ) and waist circumference (89.80 kg/m2 vs. 92.47 kg/m2 ) than GADA negative subjects; however these differences did not attain statistical significance. Subjects who were GADA positive had higher mean fasting blood glucose (144mg/dl vs. 125mg/dl, t=2.20, p=0.14), higher mean HbA1c levels (7% vs. 6.1%, t=3.19 p=0.077) and a higher proportion on insulin therapy (31.6% vs. 22%, χ 2 = 0.07, p= 0.25) when compared with GADA negative patients. Conclusion The prevalence of LADA amongst Nigerian patients clinically diagnosed as type 2 DM was 11.9%. This high prevalence emphasizes the importance of GAD antibody testing in our practice settings, so as to appropriately classify adult patients with diabetes mellitus. This would also help direct appropriate therapy so as to improve glycaemic control and reduce the risk of long term complications of diabetes mellitus