A normal DXA in a person with diabetes is not a normal answer

Bone mineral density systematically under-states fracture risk in type 2 diabetes. The bone is denser and worse: microarchitecture is disturbed, cortical porosity increased, and the density number comes out reassuring while the fracture risk is raised. Add the falls - neuropathy, postural hypotension, visual impairment, hypoglycaemia - and the patient with a T-score of -1.5 may be at higher absolute risk than someone without diabetes at -2.5.

So do not stop at the DXA. Run FRAX, and know that it under-estimates in diabetes too; the common corrections are to enter rheumatoid arthritis as a proxy, to reduce the T-score input by about half a standard deviation, or to raise the calculated risk - use whichever your local guidance endorses, and record which you used. Then look at the drug chart, because the antidiabetic agents differ in their skeletal effects, and at the falls history, which is doing at least as much work as the bone.

The practical conversion is to treat a person with diabetes and a fragility fracture, or a borderline density with falls, as someone who needs treatment now rather than a repeat scan in two years.

• Do not read a DXA in diabetes at face value - density under-states fracture risk in this group
• Apply a recognised correction when using FRAX and record which one you used
• Take a falls history in every patient with diabetes being assessed for bone health
• Review the antidiabetic drug chart for agents with adverse skeletal effects
• Treat a fragility fracture in diabetes as an indication for treatment, whatever the T-score says

Why it matters

The test most clinicians rely on to exclude the problem is the test that systematically misses it in this group.

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