Background: Vitamin D (1,25(OH)2D3) is a steroid hormone that has a range of physiological functions in skeletal and non-skeletal tissues, and can contribute to prevent and/or treat osteoporosis, obesity, and type 2 diabetes mellitus (T2DM). Vitamin D is a topic of great interest for the scientific community as well as for the layman. The commonly-know function of vitamin D has been associated with skeletal tissue, in which vitamin D influences mineralization, bone turnover rate, and occurrence of fractures, contributing to the prevention and treatment of osteoporosis. Objective: To assess vitamin D and parathyroid hormone serum levels, and correlate it with osteoporotic and fracture risk in males with type-2 diabetes. Patients and methods: This was a prospective case-control study carried out at Department of Internal Medicine, (Damietta) Faculty of Medicine, Al-Azhar University between January 2018 to January 2021. It included 70 males with type-2 diabetes mellitus, and a comparison group (control group) of 70 healthy individuals. All were submitted to full clinical assessment by history taking, clinical examinations, laboratory investigations, and DEXA scan. Vitamin and parathormone hormones were assessed and correlated with the results of DEXA scan. Results: There was no significant difference between study and control groups regarding total bilirubin or albumin. Regarding kidney function, both groups were comparable as regard to creatinine. However, serum uric acid significantly increased in study when compared to control group. In addition, fasting blood sugar and postprandial blood sugar significantly increased in study when compared to control group. There was no significant difference found between study and control groups regarding ionized calcium and phosphate. Insulin, fasting insulin and HOMA-IR significantly increased in study than compared to control group. Regarding vitamin D concentration, there was significant reduction in study when compared to control group. There was significant increase of patients with deficient vitamin D in study than control group. Regarding parathormone hormone, there was no significant difference between study and control groups. Regarding T-score, it ranged from -2.9 to 1.70, and there was a statistically significant reduction of T-score among study when compared to control group. Regarding bone disease, according to DEXA-scan, it was normal among 105 subjects. Osteopenia was reported among 12 subjects and osteoporosis in 23 subjects, and there was significant increase of osteoporosis in study than control group. There was an inverse and significant correlation between HOMA-IR from one side and each of total calcium, ionized calcium, vitamin D and DEXA scan. Conclusion: There was an association between diabetes mellitus and bone mineral density, indicating the role of diabetes mellitus as a risk factor of decreased bone density which could be exerted by different mechanisms: hyperglycemia, hypovitaminosis D, dyslipidemia and electrolyte disturbances were the major biochemical changes in this condition. All could play a role.