We conducted a clinical trial with 200 type 2 diabetes patients to evaluate mμSORS for non-invasive blood glucose measurement. Using Optical Coherence Tomography, we studied skin thickness and optical attenuation in 172 diabetic and 26 healthy subjects. Results showed thicker stratum corneum and stratum spinosum in diabetics. Epidermal thickness increased with age and BMI, decreased with skin brightness, and varied minimally with gender. Optical attenuation in stratum spinosum was lower in diabetics, decreased with increasing a*, and was minimally affected by gender and BMI but increased with age in the upper dermis. These findings support mμSORS for accurate non-invasive glucose monitoring.