Diabetes and premature menopause: is their co-existence detrimental to the skeleton?

OBJECTIVE: Premature menopause is a known risk factor for osteoporosis, whilst the influence of type 2 diabetes on bone mineral density (BMD) is still controversial. DESIGN AND METHODS: BMD values assessed by dual-energy X-ray absorptiometry (DXA) in L2-L4 vertebrae and the femoral neck (FN) of 40 diabetic women with premature menopause (D-EMP) were compared with those of 60 non-diabetic, prematurely menopausal women (EMP) and 60 diabetic women with normal menopause (D-NMP) who had been matched by age and body mass index (BMI). In all women, the time elapsed since menopause ranged between 10 and 25 years and the duration of diabetes exceeded 75% of the postmenopausal time period. The age of D-EMP women was 58.7+/-5 years (mean+/-1 s.d.), age at menopause 39.5+/-2.7, years since menopause 18.6+/-4.9, BMI 27.8+/-4.3 kg/m(2) and duration of diabetes 13.9+/-3.9 years. RESULTS: Vertebral BMD values of D-EMP women were significantly higher than those of EMP women (0.908+/-0.135 vs. 0.817+/-0.14 g/cm(2), P = 0.002), although there was no significant difference between D-EMP and D-NMP women (0.886+/-0.15 g/cm(2)). No significant differences were observed in FN BMD values between all groups. Age-adjusted BMD values (Z scores) of D-EMP women were higher than EMP women in both anatomic sites (P < 0.01), but did not differ from D-NMP women. In contrast to the other two groups, no statistically significant correlation was observed in D-EMP women between the BMD values of either anatomic area and the time elapsed since menopause. HbA(1c) values were positively correlated only to vertebral BMD values of the D-EMP group (P < 0.05). No correlation was observed between the BMD values and the duration of diabetes either in D-EMP or in D-NMP women. CONCLUSIONS: Type 2 diabetes seems to positively affect the mineral density of the trabecular bone in women with premature menopause. The duration of diabetes does not appear to influence bone mass.

Proinsulin as a possible therapeutic agent.

Gene technology has made significant amounts of biosynthetic human proinsulin (BHP) for biological and clinical studies available. It has been shown both in vitro and in vivo that BHP is about 10% as active as biosynthetic human insulin. More specifically it is 8% as potent regarding its action in stimulating peripheral glucose disposal and 12% as potent in suppressing hepatic glucose output. Its hypoglycemic effect is rather produced by the intact molecule or its intermediates and not by conversion to insulin or C-peptide. BHP appears to exert a more prolonged action when administered subcutaneously compared to NPH insulin. Furthermore because of its weaker effect on peripheral glucose utilization it is expected to create less profound hypoglycemia. Under conditions of equipotency BHP may stimulate triglyceride synthesis in a lower degree and in that way be less lipogenic. On longterm basis BHP proved to have a low immunogenic potential. We investigated the efficacy of BHP in split doses in type II diabetics with relative insulin resistance. Glucose levels at 1600 and 2000 and 0400 hrs as well as integrated glycemia over the 24 h period were lower under BHP. The potency of BHP in this and other studies has been demonstrated after application of greater quantities from it in terms of equimolarity. Nevertheless there are certain features such as the protracted action, the stronger effect on hepatic glucose production and the lower suppression of endogenous insulin secretion which make proinsulin a promising agent in the future management of type II diabetes.

Efficacy of a new needleless insulin delivery system monitoring of blood glucose fluctuations and free insulin levels.

A new insulin delivery system Vitajet has been invented which involves a high-pressure spring and obviates the use of needle injections. To study its efficacy we compared blood glucose fluctuations, integrated glycemia, free insulin and total free insulin concentrations in six insulin-dependent diabetics. After obtaining a steady state of carbohydrate metabolism overnight by feedback control through the artificial endocrine pancreas (AEP) Biostator, the patients received their usual morning and evening doses of insulin by either conventional injection or Vitajet in random order. Blood glucose levels were significantly lower after Vitajet than conventional injections (p less than 0.04) between 10 a.m. and 4 p.m., but the difference disappeared from 4 p.m. onwards. The areas under the curve (AUCs) of glucose fluctuations were lower after Vitajet (28036 +/- 4655 vs 31086 +/- 2310 mg. min% mean +/- SEM, p less than 0.01). AUCs for free insulin concentrations (microU.min/ml) were close: 39286 +/- 4510 (Vitajet) vs 30597 +/- 3575 (conventional). It is concluded that Vitajet constitutes an efficient needleless route for administering insulin pulses.

The effects of the somatostatin analogue SMS 201-995 on carbohydrate homeostasis of insulin-dependent diabetics as assessed by the artificial endocrine pancreas.

On the basis of the inhibitory actions of the somatostatin analogue SMS 201-995 on growth hormone (GH) and glucagon (IRG) secretion we investigated its effects on carbohydrate metabolism of insulin-dependent diabetics. Six patients with no residual insulin secretion were connected to the artificial endocrine pancreas (AEP) and after the establishment of a steady state overnight they were injected either normal saline or 50 micrograms of SMS 201-995 s.c., t.i.d., or 100 micrograms of the same compound b.i.d. Insulin requirements were assessed by the AEP and compared during the 24 h and after the main meals. The inhibition of GH and IRG secretion was evaluated as well. 50 micrograms of SMS analogue t.i.d. induced a significant reduction of insulin requirement (mean +/- SEM) while no significant difference was observed between control and 100 micrograms s.c., b.i.d., nor between 50 micrograms and 100 micrograms. The curve of glucose fluctuations was smoother after 50 micrograms than after 100 micrograms and control. Postprandial IRG secretion was inhibited by both regimens of SMS after lunch and dinner. GH secretion was significantly inhibited after all meals during the days of analogue administration. SMS 201-995 analogue appears to have a remarkable antidiabetic activity as shown by the sparing of administered amount of insulin, suppression of counter-insulin hormones and smoothing of blood glucose curve. It may constitute a safe and effective adjunctive measure in the management of insulin-dependent diabetics.

Differences between somatostatin-28 and somatostatin-14 with respect to their biological effects in healthy humans and acromegalics.

In order to compare the effects of somatostatin-28 (SS-28) with those of somatostatin-14 (SS-14) in humans, we administered both compounds randomly in 5 healthy persons and 3 patients with active acromegaly. Blood glucose, growth hormone, insulin, glucagon, TSH, FSH, LH and prolactin were estimated after arginine, TRH and LHRH stimulation in the normals and without stimulation in the acromegalics. Both substances were administered in doses of 25, 50, 200 and 250 micrograms. Our results indicate that SS-28 is at least 5 times more potent in man than SS-14 as far as inhibition of growth hormone, insulin, glucagon and prolactin secretion is concerned. On the other hand SS-28 is at least 2 times more potent than SS-14 in the inhibition of TSH, FSH and LH. If this difference in potency is calculated on the basis of equimolarity, the action of SS-28 becomes even much greater. According to these findings, SS-28 appears to be either the main hormone and SS-14 a fragment of it with a lesser degree of biologic activity, or the prohormone with special properties.