The study, “Type 2 diabetes mellitus complicated with idiopathic hypoparathyroidism where poor glycaemic control was associated with low adherence to exercise and medication due to hypocalcaemia,” was published in the journal BMJ Case Reports.
People with idiopathic (no known cause) hypoparathyroidism have abnormally low secretion of parathyroid hormone (PTH), which regulates calcium levels in the blood. Calcium is crucial for several functions, including bone development, blood clotting, and muscle contraction.
Low PTH levels lead to low calcium concentrations and may manifest as muscle pain (myalgia), fatigue, or weakness. Because these symptoms are common in other disorders, physicians may overlook idiopathic hypothyroidism as a possible diagnosis.
Researchers at Yokohama Rosai Hospital in Japan reported on a 36-year-old obese man who was admitted to the hospital with persistently high blood sugar and low calcium levels, or hypocalcemia.
Two months earlier, his calcium level had been 6.1 mg/dL (normal range is 8.5 to 10.5 mg/dL), and his glycated hemoglobin (HbA1c) — an indicator of diabetes — was 11.1% (less than 6% is normal). He was taking four different oral treatments per day to lower blood sugar levels: metformin, vildagliptin, mitiglinide, and voglibose.
The man — whose mother had type 2 diabetes and was receiving treatment with insulin — had a history of asthma, and was diagnosed with type 2 diabetes when he was 30. Despite effective reduction of blood sugar levels over six months, he began to complain of muscle pain in his legs, which prevented him from adequate physical exercise.
The man attributed the onset of myalgia to the prescribed treatment plan, and started to cut back on exercise and medication. His blood calcium levels were not measured at the time.
Subsequent tests revealed high blood levels of phosphate, creatine kinase — an indicator of muscle damage — and triglycerides (fat), as well as low magnesium levels and insulin resistance. He also had low levels of intact PTH and 1,25-(OH)2 vitamin D3, an active form of vitamin D.
Neurological examination showed decreased vibratory sensation and tendon reflexes (which determine muscle contraction upon tapping) in his lower limbs. Brain imaging revealed no abnormalities.
Because there was no previous medical or family history or physical or laboratory findings that would indicate another disease, the patient was diagnosed with idiopathic hypoparathyroidism. He was treated with metformin and liraglutide, and given a daily diet plan of 1,900 calories. Correction of serum calcium levels with calcitriol (an active vitamin D analog) was associated with complete relief of muscle pain.
The man was able to exercise regularly and comply with the prescribed medications and diet. Three months after discharge, he had lost weight, his serum calcium levels were stable, and his HbA1c levels were close to normal (7.1%).
While idiopathic hypoparathyroidism is a rare disease, it can make it difficult to control blood sugar levels by inducing insulin resistance, which is linked to reduced mobility, the scientists said.
“Based on our findings, we recommend checking serum calcium levels in patients with T2DM [type 2 diabetes mellitus] to identify underlying hypoparathyroidism, particularly in those who experience symptoms of myalgia,” they wrote.