Serum calcium levels are linked to higher fasting blood sugar and insulin resistance in men with type 2 diabetes, regardless of parathyroid hormone levels. This study looked at 271 men and 209 women with diabetes to see how calcium and parathyroid hormone relate to diabetes markers. The results showed that in men, higher calcium levels were associated with higher blood sugar and insulin resistance, even after considering other factors like age and weight. However, parathyroid hormone levels did not show the same connection. This suggests that calcium may play a role in glucose metabolism in men with type 2 diabetes, separate from parathyroid hormone or bone health.